/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software  Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2006 by Nicholas Bishop
 * All rights reserved.
 * Implements the Sculpt Mode tools
 */

/** \file
 * \ingroup edsculpt
 */

#include "MEM_guardedalloc.h"

#include "BLI_math.h"
#include "BLI_blenlib.h"
#include "BLI_dial_2d.h"
#include "BLI_task.h"
#include "BLI_utildefines.h"
#include "BLI_ghash.h"

#include "BLT_translation.h"

#include "DNA_customdata_types.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_node_types.h"
#include "DNA_object_types.h"
#include "DNA_scene_types.h"
#include "DNA_brush_types.h"

#include "BKE_brush.h"
#include "BKE_ccg.h"
#include "BKE_colortools.h"
#include "BKE_context.h"
#include "BKE_image.h"
#include "BKE_key.h"
#include "BKE_library.h"
#include "BKE_main.h"
#include "BKE_mesh.h"
#include "BKE_mesh_mapping.h"
#include "BKE_modifier.h"
#include "BKE_multires.h"
#include "BKE_node.h"
#include "BKE_object.h"
#include "BKE_paint.h"
#include "BKE_particle.h"
#include "BKE_pbvh.h"
#include "BKE_pointcache.h"
#include "BKE_report.h"
#include "BKE_scene.h"
#include "BKE_screen.h"
#include "BKE_subsurf.h"

#include "DEG_depsgraph.h"
#include "DEG_depsgraph_query.h"

#include "WM_api.h"
#include "WM_types.h"
#include "WM_message.h"
#include "WM_toolsystem.h"

#include "ED_sculpt.h"
#include "ED_object.h"
#include "ED_screen.h"
#include "ED_view3d.h"
#include "paint_intern.h"
#include "sculpt_intern.h"

#include "RNA_access.h"
#include "RNA_define.h"

#include "UI_interface.h"
#include "UI_resources.h"

#include "bmesh.h"
#include "bmesh_tools.h"

#include <math.h>
#include <stdlib.h>
#include <string.h>

/** \name Tool Capabilities
 *
 * Avoid duplicate checks, internal logic only,
 * share logic with #rna_def_sculpt_capabilities where possible.
 *
 * \{ */

/* Check if there are any active modifiers in stack
 * (used for flushing updates at enter/exit sculpt mode) */
static bool sculpt_has_active_modifiers(Scene *scene, Object *ob)
{
  ModifierData *md;
  VirtualModifierData virtualModifierData;

  md = modifiers_getVirtualModifierList(ob, &virtualModifierData);

  /* exception for shape keys because we can edit those */
  for (; md; md = md->next) {
    if (modifier_isEnabled(scene, md, eModifierMode_Realtime)) {
      return 1;
    }
  }

  return 0;
}

static bool sculpt_tool_needs_original(const char sculpt_tool)
{
  return ELEM(
      sculpt_tool, SCULPT_TOOL_GRAB, SCULPT_TOOL_ROTATE, SCULPT_TOOL_THUMB, SCULPT_TOOL_LAYER);
}

static bool sculpt_tool_is_proxy_used(const char sculpt_tool)
{
  return ELEM(sculpt_tool, SCULPT_TOOL_SMOOTH, SCULPT_TOOL_LAYER);
}

static bool sculpt_brush_use_topology_rake(const SculptSession *ss, const Brush *brush)
{
  return SCULPT_TOOL_HAS_TOPOLOGY_RAKE(brush->sculpt_tool) &&
         (brush->topology_rake_factor > 0.0f) && (ss->bm != NULL);
}

/**
 * Test whether the #StrokeCache.sculpt_normal needs update in #do_brush_action
 */
static int sculpt_brush_needs_normal(const SculptSession *ss, const Brush *brush)
{
  return ((SCULPT_TOOL_HAS_NORMAL_WEIGHT(brush->sculpt_tool) &&
           (ss->cache->normal_weight > 0.0f)) ||

          ELEM(brush->sculpt_tool,
               SCULPT_TOOL_BLOB,
               SCULPT_TOOL_CREASE,
               SCULPT_TOOL_DRAW,
               SCULPT_TOOL_LAYER,
               SCULPT_TOOL_NUDGE,
               SCULPT_TOOL_ROTATE,
               SCULPT_TOOL_THUMB) ||

          (brush->mtex.brush_map_mode == MTEX_MAP_MODE_AREA)) ||
         sculpt_brush_use_topology_rake(ss, brush);
}
/** \} */

static bool sculpt_brush_needs_rake_rotation(const Brush *brush)
{
  return SCULPT_TOOL_HAS_RAKE(brush->sculpt_tool) && (brush->rake_factor != 0.0f);
}

typedef enum StrokeFlags {
  CLIP_X = 1,
  CLIP_Y = 2,
  CLIP_Z = 4,
} StrokeFlags;

/************** Access to original unmodified vertex data *************/

typedef struct {
  BMLog *bm_log;

  SculptUndoNode *unode;
  float (*coords)[3];
  short (*normals)[3];
  const float *vmasks;

  /* Original coordinate, normal, and mask */
  const float *co;
  const short *no;
  float mask;
} SculptOrigVertData;

/* Initialize a SculptOrigVertData for accessing original vertex data;
 * handles BMesh, mesh, and multires */
static void sculpt_orig_vert_data_unode_init(SculptOrigVertData *data,
                                             Object *ob,
                                             SculptUndoNode *unode)
{
  SculptSession *ss = ob->sculpt;
  BMesh *bm = ss->bm;

  memset(data, 0, sizeof(*data));
  data->unode = unode;

  if (bm) {
    data->bm_log = ss->bm_log;
  }
  else {
    data->coords = data->unode->co;
    data->normals = data->unode->no;
    data->vmasks = data->unode->mask;
  }
}

/* Initialize a SculptOrigVertData for accessing original vertex data;
 * handles BMesh, mesh, and multires */
static void sculpt_orig_vert_data_init(SculptOrigVertData *data, Object *ob, PBVHNode *node)
{
  SculptUndoNode *unode;
  unode = sculpt_undo_push_node(ob, node, SCULPT_UNDO_COORDS);
  sculpt_orig_vert_data_unode_init(data, ob, unode);
}

/* Update a SculptOrigVertData for a particular vertex from the PBVH
 * iterator */
static void sculpt_orig_vert_data_update(SculptOrigVertData *orig_data, PBVHVertexIter *iter)
{
  if (orig_data->unode->type == SCULPT_UNDO_COORDS) {
    if (orig_data->bm_log) {
      BM_log_original_vert_data(orig_data->bm_log, iter->bm_vert, &orig_data->co, &orig_data->no);
    }
    else {
      orig_data->co = orig_data->coords[iter->i];
      orig_data->no = orig_data->normals[iter->i];
    }
  }
  else if (orig_data->unode->type == SCULPT_UNDO_MASK) {
    if (orig_data->bm_log) {
      orig_data->mask = BM_log_original_mask(orig_data->bm_log, iter->bm_vert);
    }
    else {
      orig_data->mask = orig_data->vmasks[iter->i];
    }
  }
}

static void sculpt_rake_data_update(struct SculptRakeData *srd, const float co[3])
{
  float rake_dist = len_v3v3(srd->follow_co, co);
  if (rake_dist > srd->follow_dist) {
    interp_v3_v3v3(srd->follow_co, srd->follow_co, co, rake_dist - srd->follow_dist);
  }
}

static void sculpt_rake_rotate(const SculptSession *ss,
                               const float sculpt_co[3],
                               const float v_co[3],
                               float factor,
                               float r_delta[3])
{
  float vec_rot[3];

#if 0
  /* lerp */
  sub_v3_v3v3(vec_rot, v_co, sculpt_co);
  mul_qt_v3(ss->cache->rake_rotation_symmetry, vec_rot);
  add_v3_v3(vec_rot, sculpt_co);
  sub_v3_v3v3(r_delta, vec_rot, v_co);
  mul_v3_fl(r_delta, factor);
#else
  /* slerp */
  float q_interp[4];
  sub_v3_v3v3(vec_rot, v_co, sculpt_co);

  copy_qt_qt(q_interp, ss->cache->rake_rotation_symmetry);
  pow_qt_fl_normalized(q_interp, factor);
  mul_qt_v3(q_interp, vec_rot);

  add_v3_v3(vec_rot, sculpt_co);
  sub_v3_v3v3(r_delta, vec_rot, v_co);
#endif
}

/**
 * Align the grab delta to the brush normal.
 *
 * \param grab_delta: Typically from `ss->cache->grab_delta_symmetry`.
 */
static void sculpt_project_v3_normal_align(SculptSession *ss,
                                           const float normal_weight,
                                           float grab_delta[3])
{
  /* signed to support grabbing in (to make a hole) as well as out. */
  const float len_signed = dot_v3v3(ss->cache->sculpt_normal_symm, grab_delta);

  /* this scale effectively projects the offset so dragging follows the cursor,
   * as the normal points towards the view, the scale increases. */
  float len_view_scale;
  {
    float view_aligned_normal[3];
    project_plane_v3_v3v3(
        view_aligned_normal, ss->cache->sculpt_normal_symm, ss->cache->view_normal);
    len_view_scale = fabsf(dot_v3v3(view_aligned_normal, ss->cache->sculpt_normal_symm));
    len_view_scale = (len_view_scale > FLT_EPSILON) ? 1.0f / len_view_scale : 1.0f;
  }

  mul_v3_fl(grab_delta, 1.0f - normal_weight);
  madd_v3_v3fl(
      grab_delta, ss->cache->sculpt_normal_symm, (len_signed * normal_weight) * len_view_scale);
}

/** \name SculptProjectVector
 *
 * Fast-path for #project_plane_v3_v3v3
 *
 * \{ */

typedef struct SculptProjectVector {
  float plane[3];
  float len_sq;
  float len_sq_inv_neg;
  bool is_valid;

} SculptProjectVector;

/**
 * \param plane: Direction, can be any length.
 */
static void sculpt_project_v3_cache_init(SculptProjectVector *spvc, const float plane[3])
{
  copy_v3_v3(spvc->plane, plane);
  spvc->len_sq = len_squared_v3(spvc->plane);
  spvc->is_valid = (spvc->len_sq > FLT_EPSILON);
  spvc->len_sq_inv_neg = (spvc->is_valid) ? -1.0f / spvc->len_sq : 0.0f;
}

/**
 * Calculate the projection.
 */
static void sculpt_project_v3(const SculptProjectVector *spvc, const float vec[3], float r_vec[3])
{
#if 0
  project_plane_v3_v3v3(r_vec, vec, spvc->plane);
#else
  /* inline the projection, cache `-1.0 / dot_v3_v3(v_proj, v_proj)` */
  madd_v3_v3fl(r_vec, spvc->plane, dot_v3v3(vec, spvc->plane) * spvc->len_sq_inv_neg);
#endif
}

/** \} */

/**********************************************************************/

/* Returns true if the stroke will use dynamic topology, false
 * otherwise.
 *
 * Factors: some brushes like grab cannot do dynamic topology.
 * Others, like smooth, are better without. Same goes for alt-
 * key smoothing. */
static bool sculpt_stroke_is_dynamic_topology(const SculptSession *ss, const Brush *brush)
{
  return ((BKE_pbvh_type(ss->pbvh) == PBVH_BMESH) &&

          (!ss->cache || (!ss->cache->alt_smooth)) &&

          /* Requires mesh restore, which doesn't work with
           * dynamic-topology */
          !(brush->flag & BRUSH_ANCHORED) && !(brush->flag & BRUSH_DRAG_DOT) &&

          SCULPT_TOOL_HAS_DYNTOPO(brush->sculpt_tool));
}

/*** paint mesh ***/

static void paint_mesh_restore_co_task_cb(void *__restrict userdata,
                                          const int n,
                                          const ParallelRangeTLS *__restrict UNUSED(tls))
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;

  SculptUndoNode *unode;
  SculptUndoType type = (data->brush->sculpt_tool == SCULPT_TOOL_MASK ? SCULPT_UNDO_MASK :
                                                                        SCULPT_UNDO_COORDS);

  if (ss->bm) {
    unode = sculpt_undo_push_node(data->ob, data->nodes[n], type);
  }
  else {
    unode = sculpt_undo_get_node(data->nodes[n]);
  }

  if (unode) {
    PBVHVertexIter vd;
    SculptOrigVertData orig_data;

    sculpt_orig_vert_data_unode_init(&orig_data, data->ob, unode);

    BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
    {
      sculpt_orig_vert_data_update(&orig_data, &vd);

      if (orig_data.unode->type == SCULPT_UNDO_COORDS) {
        copy_v3_v3(vd.co, orig_data.co);
        if (vd.no) {
          copy_v3_v3_short(vd.no, orig_data.no);
        }
        else {
          normal_short_to_float_v3(vd.fno, orig_data.no);
        }
      }
      else if (orig_data.unode->type == SCULPT_UNDO_MASK) {
        *vd.mask = orig_data.mask;
      }

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
    BKE_pbvh_vertex_iter_end;

    BKE_pbvh_node_mark_update(data->nodes[n]);
  }
}

static void paint_mesh_restore_co(Sculpt *sd, Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  PBVHNode **nodes;
  int totnode;

  BKE_pbvh_search_gather(ss->pbvh, NULL, NULL, &nodes, &totnode);

  /**
   * Disable OpenMP when dynamic-topology is enabled. Otherwise, new entries might be inserted by
   * #sculpt_undo_push_node() into the GHash used internally by #BM_log_original_vert_co()
   * by a different thread. See T33787. */
  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && !ss->bm &&
                            totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, paint_mesh_restore_co_task_cb, &settings);

  if (nodes) {
    MEM_freeN(nodes);
  }
}

/*** BVH Tree ***/

static void sculpt_extend_redraw_rect_previous(Object *ob, rcti *rect)
{
  /* expand redraw rect with redraw rect from previous step to
   * prevent partial-redraw issues caused by fast strokes. This is
   * needed here (not in sculpt_flush_update) as it was before
   * because redraw rectangle should be the same in both of
   * optimized PBVH draw function and 3d view redraw (if not -- some
   * mesh parts could disappear from screen (sergey) */
  SculptSession *ss = ob->sculpt;

  if (ss->cache) {
    if (!BLI_rcti_is_empty(&ss->cache->previous_r)) {
      BLI_rcti_union(rect, &ss->cache->previous_r);
    }
  }
}

/* Get a screen-space rectangle of the modified area */
bool sculpt_get_redraw_rect(ARegion *ar, RegionView3D *rv3d, Object *ob, rcti *rect)
{
  PBVH *pbvh = ob->sculpt->pbvh;
  float bb_min[3], bb_max[3];

  if (!pbvh) {
    return 0;
  }

  BKE_pbvh_redraw_BB(pbvh, bb_min, bb_max);

  /* convert 3D bounding box to screen space */
  if (!paint_convert_bb_to_rect(rect, bb_min, bb_max, ar, rv3d, ob)) {
    return 0;
  }

  return 1;
}

void ED_sculpt_redraw_planes_get(float planes[4][4], ARegion *ar, Object *ob)
{
  PBVH *pbvh = ob->sculpt->pbvh;
  /* copy here, original will be used below */
  rcti rect = ob->sculpt->cache->current_r;

  sculpt_extend_redraw_rect_previous(ob, &rect);

  paint_calc_redraw_planes(planes, ar, ob, &rect);

  /* we will draw this rect, so now we can set it as the previous partial rect.
   * Note that we don't update with the union of previous/current (rect), only with
   * the current. Thus we avoid the rectangle needlessly growing to include
   * all the stroke area */
  ob->sculpt->cache->previous_r = ob->sculpt->cache->current_r;

  /* clear redraw flag from nodes */
  if (pbvh) {
    BKE_pbvh_update_bounds(pbvh, PBVH_UpdateRedraw);
  }
}

/************************ Brush Testing *******************/

void sculpt_brush_test_init(SculptSession *ss, SculptBrushTest *test)
{
  RegionView3D *rv3d = ss->cache->vc->rv3d;

  test->radius_squared = ss->cache->radius_squared;
  copy_v3_v3(test->location, ss->cache->location);
  test->dist = 0.0f; /* just for initialize */

  /* Only for 2D projection. */
  zero_v4(test->plane_view);
  zero_v4(test->plane_tool);

  test->mirror_symmetry_pass = ss->cache->mirror_symmetry_pass;

  if (rv3d->rflag & RV3D_CLIPPING) {
    test->clip_rv3d = rv3d;
  }
  else {
    test->clip_rv3d = NULL;
  }
}

BLI_INLINE bool sculpt_brush_test_clipping(const SculptBrushTest *test, const float co[3])
{
  RegionView3D *rv3d = test->clip_rv3d;
  if (!rv3d) {
    return false;
  }
  float symm_co[3];
  flip_v3_v3(symm_co, co, test->mirror_symmetry_pass);
  return ED_view3d_clipping_test(rv3d, symm_co, true);
}

bool sculpt_brush_test_sphere(SculptBrushTest *test, const float co[3])
{
  float distsq = len_squared_v3v3(co, test->location);

  if (distsq <= test->radius_squared) {
    if (sculpt_brush_test_clipping(test, co)) {
      return 0;
    }
    test->dist = sqrtf(distsq);
    return 1;
  }
  else {
    return 0;
  }
}

bool sculpt_brush_test_sphere_sq(SculptBrushTest *test, const float co[3])
{
  float distsq = len_squared_v3v3(co, test->location);

  if (distsq <= test->radius_squared) {
    if (sculpt_brush_test_clipping(test, co)) {
      return 0;
    }
    test->dist = distsq;
    return 1;
  }
  else {
    return 0;
  }
}

bool sculpt_brush_test_sphere_fast(const SculptBrushTest *test, const float co[3])
{
  if (sculpt_brush_test_clipping(test, co)) {
    return 0;
  }
  return len_squared_v3v3(co, test->location) <= test->radius_squared;
}

bool sculpt_brush_test_circle_sq(SculptBrushTest *test, const float co[3])
{
  float co_proj[3];
  closest_to_plane_normalized_v3(co_proj, test->plane_view, co);
  float distsq = len_squared_v3v3(co_proj, test->location);

  if (distsq <= test->radius_squared) {
    if (sculpt_brush_test_clipping(test, co)) {
      return 0;
    }
    test->dist = distsq;
    return 1;
  }
  else {
    return 0;
  }
}

bool sculpt_brush_test_cube(SculptBrushTest *test, const float co[3], float local[4][4])
{
  float side = M_SQRT1_2;
  float local_co[3];

  if (sculpt_brush_test_clipping(test, co)) {
    return 0;
  }

  mul_v3_m4v3(local_co, local, co);

  local_co[0] = fabsf(local_co[0]);
  local_co[1] = fabsf(local_co[1]);
  local_co[2] = fabsf(local_co[2]);

  if (local_co[0] <= side && local_co[1] <= side && local_co[2] <= side) {
    float p = 4.0f;

    test->dist = ((powf(local_co[0], p) + powf(local_co[1], p) + powf(local_co[2], p)) /
                  powf(side, p));

    return 1;
  }
  else {
    return 0;
  }
}

SculptBrushTestFn sculpt_brush_test_init_with_falloff_shape(SculptSession *ss,
                                                            SculptBrushTest *test,
                                                            char falloff_shape)
{
  sculpt_brush_test_init(ss, test);
  SculptBrushTestFn sculpt_brush_test_sq_fn;
  if (falloff_shape == PAINT_FALLOFF_SHAPE_SPHERE) {
    sculpt_brush_test_sq_fn = sculpt_brush_test_sphere_sq;
  }
  else {
    /* PAINT_FALLOFF_SHAPE_TUBE */
    plane_from_point_normal_v3(test->plane_view, test->location, ss->cache->view_normal);
    sculpt_brush_test_sq_fn = sculpt_brush_test_circle_sq;
  }
  return sculpt_brush_test_sq_fn;
}

const float *sculpt_brush_frontface_normal_from_falloff_shape(SculptSession *ss,
                                                              char falloff_shape)
{
  if (falloff_shape == PAINT_FALLOFF_SHAPE_SPHERE) {
    return ss->cache->sculpt_normal_symm;
  }
  else {
    /* PAINT_FALLOFF_SHAPE_TUBE */
    return ss->cache->view_normal;
  }
}

static float frontface(const Brush *br,
                       const float sculpt_normal[3],
                       const short no[3],
                       const float fno[3])
{
  if (br->flag & BRUSH_FRONTFACE) {
    float dot;

    if (no) {
      float tmp[3];

      normal_short_to_float_v3(tmp, no);
      dot = dot_v3v3(tmp, sculpt_normal);
    }
    else {
      dot = dot_v3v3(fno, sculpt_normal);
    }
    return dot > 0 ? dot : 0;
  }
  else {
    return 1;
  }
}

#if 0

static bool sculpt_brush_test_cyl(SculptBrushTest *test,
                                  float co[3],
                                  float location[3],
                                  const float area_no[3])
{
  if (sculpt_brush_test_sphere_fast(test, co)) {
    float t1[3], t2[3], t3[3], dist;

    sub_v3_v3v3(t1, location, co);
    sub_v3_v3v3(t2, x2, location);

    cross_v3_v3v3(t3, area_no, t1);

    dist = len_v3(t3) / len_v3(t2);

    test->dist = dist;

    return 1;
  }

  return 0;
}

#endif

/* ===== Sculpting =====
 */
static void flip_v3(float v[3], const char symm)
{
  flip_v3_v3(v, v, symm);
}

static float calc_overlap(StrokeCache *cache, const char symm, const char axis, const float angle)
{
  float mirror[3];
  float distsq;

  /* flip_v3_v3(mirror, cache->traced_location, symm); */
  flip_v3_v3(mirror, cache->true_location, symm);

  if (axis != 0) {
    float mat[3][3];
    axis_angle_to_mat3_single(mat, axis, angle);
    mul_m3_v3(mat, mirror);
  }

  /* distsq = len_squared_v3v3(mirror, cache->traced_location); */
  distsq = len_squared_v3v3(mirror, cache->true_location);

  if (distsq <= 4.0f * (cache->radius_squared)) {
    return (2.0f * (cache->radius) - sqrtf(distsq)) / (2.0f * (cache->radius));
  }
  else {
    return 0;
  }
}

static float calc_radial_symmetry_feather(Sculpt *sd,
                                          StrokeCache *cache,
                                          const char symm,
                                          const char axis)
{
  int i;
  float overlap;

  overlap = 0;
  for (i = 1; i < sd->radial_symm[axis - 'X']; ++i) {
    const float angle = 2 * M_PI * i / sd->radial_symm[axis - 'X'];
    overlap += calc_overlap(cache, symm, axis, angle);
  }

  return overlap;
}

static float calc_symmetry_feather(Sculpt *sd, StrokeCache *cache)
{
  if (sd->paint.symmetry_flags & PAINT_SYMMETRY_FEATHER) {
    float overlap;
    int symm = cache->symmetry;
    int i;

    overlap = 0;
    for (i = 0; i <= symm; i++) {
      if (i == 0 || (symm & i && (symm != 5 || i != 3) && (symm != 6 || (i != 3 && i != 5)))) {

        overlap += calc_overlap(cache, i, 0, 0);

        overlap += calc_radial_symmetry_feather(sd, cache, i, 'X');
        overlap += calc_radial_symmetry_feather(sd, cache, i, 'Y');
        overlap += calc_radial_symmetry_feather(sd, cache, i, 'Z');
      }
    }

    return 1 / overlap;
  }
  else {
    return 1;
  }
}

/** \name Calculate Normal and Center
 *
 * Calculate geometry surrounding the brush center.
 * (optionally using original coordinates).
 *
 * Functions are:
 * - #calc_area_center
 * - #calc_area_normal
 * - #calc_area_normal_and_center
 *
 * \note These are all _very_ similar, when changing one, check others.
 * \{ */

static void calc_area_normal_and_center_task_cb(void *__restrict userdata,
                                                const int n,
                                                const ParallelRangeTLS *__restrict UNUSED(tls))
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  float(*area_nos)[3] = data->area_nos;
  float(*area_cos)[3] = data->area_cos;

  PBVHVertexIter vd;
  SculptUndoNode *unode = NULL;

  float private_co[2][3] = {{0.0f}};
  float private_no[2][3] = {{0.0f}};
  int private_count[2] = {0};
  bool use_original = false;

  if (ss->cache->original) {
    unode = sculpt_undo_push_node(data->ob, data->nodes[n], SCULPT_UNDO_COORDS);
    use_original = (unode->co || unode->bm_entry);
  }

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  /* when the mesh is edited we can't rely on original coords
   * (original mesh may not even have verts in brush radius) */
  if (use_original && data->has_bm_orco) {
    float(*orco_coords)[3];
    int(*orco_tris)[3];
    int orco_tris_num;
    int i;

    BKE_pbvh_node_get_bm_orco_data(data->nodes[n], &orco_tris, &orco_tris_num, &orco_coords);

    for (i = 0; i < orco_tris_num; i++) {
      const float *co_tri[3] = {
          orco_coords[orco_tris[i][0]],
          orco_coords[orco_tris[i][1]],
          orco_coords[orco_tris[i][2]],
      };
      float co[3];

      closest_on_tri_to_point_v3(co, test.location, UNPACK3(co_tri));

      if (sculpt_brush_test_sq_fn(&test, co)) {
        float no[3];
        int flip_index;

        normal_tri_v3(no, UNPACK3(co_tri));

        flip_index = (dot_v3v3(ss->cache->view_normal, no) <= 0.0f);
        if (area_cos) {
          add_v3_v3(private_co[flip_index], co);
        }
        if (area_nos) {
          add_v3_v3(private_no[flip_index], no);
        }
        private_count[flip_index] += 1;
      }
    }
  }
  else {
    BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
    {
      const float *co;
      const short *no_s; /* bm_vert only */

      if (use_original) {
        if (unode->bm_entry) {
          BM_log_original_vert_data(ss->bm_log, vd.bm_vert, &co, &no_s);
        }
        else {
          co = unode->co[vd.i];
          no_s = unode->no[vd.i];
        }
      }
      else {
        co = vd.co;
      }

      if (sculpt_brush_test_sq_fn(&test, co)) {
        float no_buf[3];
        const float *no;
        int flip_index;

        if (use_original) {
          normal_short_to_float_v3(no_buf, no_s);
          no = no_buf;
        }
        else {
          if (vd.no) {
            normal_short_to_float_v3(no_buf, vd.no);
            no = no_buf;
          }
          else {
            no = vd.fno;
          }
        }

        flip_index = (dot_v3v3(ss->cache->view_normal, no) <= 0.0f);
        if (area_cos) {
          add_v3_v3(private_co[flip_index], co);
        }
        if (area_nos) {
          add_v3_v3(private_no[flip_index], no);
        }
        private_count[flip_index] += 1;
      }
    }
    BKE_pbvh_vertex_iter_end;
  }

  BLI_mutex_lock(&data->mutex);

  /* for flatten center */
  if (area_cos) {
    add_v3_v3(area_cos[0], private_co[0]);
    add_v3_v3(area_cos[1], private_co[1]);
  }

  /* for area normal */
  if (area_nos) {
    add_v3_v3(area_nos[0], private_no[0]);
    add_v3_v3(area_nos[1], private_no[1]);
  }

  /* weights */
  data->count[0] += private_count[0];
  data->count[1] += private_count[1];

  BLI_mutex_unlock(&data->mutex);
}

static void calc_area_center(
    Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float r_area_co[3])
{
  const Brush *brush = BKE_paint_brush(&sd->paint);
  SculptSession *ss = ob->sculpt;
  const bool has_bm_orco = ss->bm && sculpt_stroke_is_dynamic_topology(ss, brush);
  int n;

  /* 0=towards view, 1=flipped */
  float area_cos[2][3] = {{0.0f}};

  int count[2] = {0};

  /* Intentionally set 'sd' to NULL since we share logic with vertex paint. */
  SculptThreadedTaskData data = {
      .sd = NULL,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .totnode = totnode,
      .has_bm_orco = has_bm_orco,
      .area_cos = area_cos,
      .area_nos = NULL,
      .count = count,
  };
  BLI_mutex_init(&data.mutex);

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, calc_area_normal_and_center_task_cb, &settings);

  BLI_mutex_end(&data.mutex);

  /* for flatten center */
  for (n = 0; n < ARRAY_SIZE(area_cos); n++) {
    if (count[n] != 0) {
      mul_v3_v3fl(r_area_co, area_cos[n], 1.0f / count[n]);
      break;
    }
  }
  if (n == 2) {
    zero_v3(r_area_co);
  }
}

static void calc_area_normal(
    Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float r_area_no[3])
{
  const Brush *brush = BKE_paint_brush(&sd->paint);
  bool use_threading = (sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT;
  sculpt_pbvh_calc_area_normal(brush, ob, nodes, totnode, use_threading, r_area_no);
}

/* expose 'calc_area_normal' externally. */
void sculpt_pbvh_calc_area_normal(const Brush *brush,
                                  Object *ob,
                                  PBVHNode **nodes,
                                  int totnode,
                                  bool use_threading,
                                  float r_area_no[3])
{
  SculptSession *ss = ob->sculpt;
  const bool has_bm_orco = ss->bm && sculpt_stroke_is_dynamic_topology(ss, brush);

  /* 0=towards view, 1=flipped */
  float area_nos[2][3] = {{0.0f}};

  int count[2] = {0};

  /* Intentionally set 'sd' to NULL since this is used for vertex paint too. */
  SculptThreadedTaskData data = {
      .sd = NULL,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .totnode = totnode,
      .has_bm_orco = has_bm_orco,
      .area_cos = NULL,
      .area_nos = area_nos,
      .count = count,
  };
  BLI_mutex_init(&data.mutex);

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = use_threading;
  BLI_task_parallel_range(0, totnode, &data, calc_area_normal_and_center_task_cb, &settings);

  BLI_mutex_end(&data.mutex);

  /* for area normal */
  for (int i = 0; i < ARRAY_SIZE(area_nos); i++) {
    if (normalize_v3_v3(r_area_no, area_nos[i]) != 0.0f) {
      break;
    }
  }
}

/* this calculates flatten center and area normal together,
 * amortizing the memory bandwidth and loop overhead to calculate both at the same time */
static void calc_area_normal_and_center(
    Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float r_area_no[3], float r_area_co[3])
{
  const Brush *brush = BKE_paint_brush(&sd->paint);
  SculptSession *ss = ob->sculpt;
  const bool has_bm_orco = ss->bm && sculpt_stroke_is_dynamic_topology(ss, brush);
  int n;

  /* 0=towards view, 1=flipped */
  float area_cos[2][3] = {{0.0f}};
  float area_nos[2][3] = {{0.0f}};

  int count[2] = {0};

  /* Intentionally set 'sd' to NULL since this is used for vertex paint too. */
  SculptThreadedTaskData data = {
      .sd = NULL,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .totnode = totnode,
      .has_bm_orco = has_bm_orco,
      .area_cos = area_cos,
      .area_nos = area_nos,
      .count = count,
  };
  BLI_mutex_init(&data.mutex);

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, calc_area_normal_and_center_task_cb, &settings);

  BLI_mutex_end(&data.mutex);

  /* for flatten center */
  for (n = 0; n < ARRAY_SIZE(area_cos); n++) {
    if (count[n] != 0) {
      mul_v3_v3fl(r_area_co, area_cos[n], 1.0f / count[n]);
      break;
    }
  }
  if (n == 2) {
    zero_v3(r_area_co);
  }

  /* for area normal */
  for (n = 0; n < ARRAY_SIZE(area_nos); n++) {
    if (normalize_v3_v3(r_area_no, area_nos[n]) != 0.0f) {
      break;
    }
  }
}

/** \} */

/* Return modified brush strength. Includes the direction of the brush, positive
 * values pull vertices, negative values push. Uses tablet pressure and a
 * special multiplier found experimentally to scale the strength factor. */
static float brush_strength(const Sculpt *sd,
                            const StrokeCache *cache,
                            const float feather,
                            const UnifiedPaintSettings *ups)
{
  const Scene *scene = cache->vc->scene;
  const Brush *brush = BKE_paint_brush((Paint *)&sd->paint);

  /* Primary strength input; square it to make lower values more sensitive */
  const float root_alpha = BKE_brush_alpha_get(scene, brush);
  float alpha = root_alpha * root_alpha;
  float dir = (brush->flag & BRUSH_DIR_IN) ? -1 : 1;
  float pressure = BKE_brush_use_alpha_pressure(scene, brush) ? cache->pressure : 1;
  float pen_flip = cache->pen_flip ? -1 : 1;
  float invert = cache->invert ? -1 : 1;
  float overlap = ups->overlap_factor;
  /* spacing is integer percentage of radius, divide by 50 to get
   * normalized diameter */

  float flip = dir * invert * pen_flip;

  switch (brush->sculpt_tool) {
    case SCULPT_TOOL_CLAY:
    case SCULPT_TOOL_CLAY_STRIPS:
    case SCULPT_TOOL_DRAW:
    case SCULPT_TOOL_LAYER:
      return alpha * flip * pressure * overlap * feather;

    case SCULPT_TOOL_MASK:
      overlap = (1 + overlap) / 2;
      switch ((BrushMaskTool)brush->mask_tool) {
        case BRUSH_MASK_DRAW:
          return alpha * flip * pressure * overlap * feather;
        case BRUSH_MASK_SMOOTH:
          return alpha * pressure * feather;
      }
      BLI_assert(!"Not supposed to happen");
      return 0.0f;

    case SCULPT_TOOL_CREASE:
    case SCULPT_TOOL_BLOB:
      return alpha * flip * pressure * overlap * feather;

    case SCULPT_TOOL_INFLATE:
      if (flip > 0) {
        return 0.250f * alpha * flip * pressure * overlap * feather;
      }
      else {
        return 0.125f * alpha * flip * pressure * overlap * feather;
      }

    case SCULPT_TOOL_FILL:
    case SCULPT_TOOL_SCRAPE:
    case SCULPT_TOOL_FLATTEN:
      if (flip > 0) {
        overlap = (1 + overlap) / 2;
        return alpha * flip * pressure * overlap * feather;
      }
      else {
        /* reduce strength for DEEPEN, PEAKS, and CONTRAST */
        return 0.5f * alpha * flip * pressure * overlap * feather;
      }

    case SCULPT_TOOL_SMOOTH:
      return alpha * pressure * feather;

    case SCULPT_TOOL_PINCH:
      if (flip > 0) {
        return alpha * flip * pressure * overlap * feather;
      }
      else {
        return 0.25f * alpha * flip * pressure * overlap * feather;
      }

    case SCULPT_TOOL_NUDGE:
      overlap = (1 + overlap) / 2;
      return alpha * pressure * overlap * feather;

    case SCULPT_TOOL_THUMB:
      return alpha * pressure * feather;

    case SCULPT_TOOL_SNAKE_HOOK:
      return root_alpha * feather;

    case SCULPT_TOOL_GRAB:
      return root_alpha * feather;

    case SCULPT_TOOL_ROTATE:
      return alpha * pressure * feather;

    default:
      return 0;
  }
}

/* Return a multiplier for brush strength on a particular vertex. */
float tex_strength(SculptSession *ss,
                   const Brush *br,
                   const float brush_point[3],
                   const float len,
                   const short vno[3],
                   const float fno[3],
                   const float mask,
                   const int thread_id)
{
  StrokeCache *cache = ss->cache;
  const Scene *scene = cache->vc->scene;
  const MTex *mtex = &br->mtex;
  float avg = 1;
  float rgba[4];
  float point[3];

  sub_v3_v3v3(point, brush_point, cache->plane_offset);

  if (!mtex->tex) {
    avg = 1;
  }
  else if (mtex->brush_map_mode == MTEX_MAP_MODE_3D) {
    /* Get strength by feeding the vertex
     * location directly into a texture */
    avg = BKE_brush_sample_tex_3d(scene, br, point, rgba, 0, ss->tex_pool);
  }
  else if (ss->texcache) {
    float symm_point[3], point_2d[2];
    float x = 0.0f, y = 0.0f; /* Quite warnings */

    /* if the active area is being applied for symmetry, flip it
     * across the symmetry axis and rotate it back to the original
     * position in order to project it. This insures that the
     * brush texture will be oriented correctly. */

    flip_v3_v3(symm_point, point, cache->mirror_symmetry_pass);

    if (cache->radial_symmetry_pass) {
      mul_m4_v3(cache->symm_rot_mat_inv, symm_point);
    }

    ED_view3d_project_float_v2_m4(cache->vc->ar, symm_point, point_2d, cache->projection_mat);

    /* still no symmetry supported for other paint modes.
     * Sculpt does it DIY */
    if (mtex->brush_map_mode == MTEX_MAP_MODE_AREA) {
      /* Similar to fixed mode, but projects from brush angle
       * rather than view direction */

      mul_m4_v3(cache->brush_local_mat, symm_point);

      x = symm_point[0];
      y = symm_point[1];

      x *= br->mtex.size[0];
      y *= br->mtex.size[1];

      x += br->mtex.ofs[0];
      y += br->mtex.ofs[1];

      avg = paint_get_tex_pixel(&br->mtex, x, y, ss->tex_pool, thread_id);

      avg += br->texture_sample_bias;
    }
    else {
      const float point_3d[3] = {point_2d[0], point_2d[1], 0.0f};
      avg = BKE_brush_sample_tex_3d(scene, br, point_3d, rgba, 0, ss->tex_pool);
    }
  }

  /* Falloff curve */
  avg *= BKE_brush_curve_strength(br, len, cache->radius);

  avg *= frontface(br, cache->view_normal, vno, fno);

  /* Paint mask */
  avg *= 1.0f - mask;

  return avg;
}

/* Test AABB against sphere */
bool sculpt_search_sphere_cb(PBVHNode *node, void *data_v)
{
  SculptSearchSphereData *data = data_v;
  float *center = data->ss->cache->location, nearest[3];
  float t[3], bb_min[3], bb_max[3];
  int i;

  if (data->original) {
    BKE_pbvh_node_get_original_BB(node, bb_min, bb_max);
  }
  else {
    BKE_pbvh_node_get_BB(node, bb_min, bb_max);
  }

  for (i = 0; i < 3; ++i) {
    if (bb_min[i] > center[i]) {
      nearest[i] = bb_min[i];
    }
    else if (bb_max[i] < center[i]) {
      nearest[i] = bb_max[i];
    }
    else {
      nearest[i] = center[i];
    }
  }

  sub_v3_v3v3(t, center, nearest);

  return len_squared_v3(t) < data->radius_squared;
}

/* 2D projection (distance to line). */
bool sculpt_search_circle_cb(PBVHNode *node, void *data_v)
{
  SculptSearchCircleData *data = data_v;
  float bb_min[3], bb_max[3];

  if (data->original) {
    BKE_pbvh_node_get_original_BB(node, bb_min, bb_max);
  }
  else {
    BKE_pbvh_node_get_BB(node, bb_min, bb_min);
  }

  float dummy_co[3], dummy_depth;
  const float dist_sq = dist_squared_ray_to_aabb_v3(
      data->dist_ray_to_aabb_precalc, bb_min, bb_max, dummy_co, &dummy_depth);

  return dist_sq < data->radius_squared || 1;
}

/* Handles clipping against a mirror modifier and SCULPT_LOCK axis flags */
static void sculpt_clip(Sculpt *sd, SculptSession *ss, float co[3], const float val[3])
{
  int i;

  for (i = 0; i < 3; ++i) {
    if (sd->flags & (SCULPT_LOCK_X << i)) {
      continue;
    }

    if ((ss->cache->flag & (CLIP_X << i)) && (fabsf(co[i]) <= ss->cache->clip_tolerance[i])) {
      co[i] = 0.0f;
    }
    else {
      co[i] = val[i];
    }
  }
}

static PBVHNode **sculpt_pbvh_gather_generic(Object *ob,
                                             Sculpt *sd,
                                             const Brush *brush,
                                             bool use_original,
                                             float radius_scale,
                                             int *r_totnode)
{
  SculptSession *ss = ob->sculpt;
  PBVHNode **nodes = NULL;

  /* Build a list of all nodes that are potentially within the brush's area of influence */
  if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_SPHERE) {
    SculptSearchSphereData data = {
        .ss = ss,
        .sd = sd,
        .radius_squared = SQUARE(ss->cache->radius * radius_scale),
        .original = use_original,
    };
    BKE_pbvh_search_gather(ss->pbvh, sculpt_search_sphere_cb, &data, &nodes, r_totnode);
  }
  else {
    struct DistRayAABB_Precalc dist_ray_to_aabb_precalc;
    dist_squared_ray_to_aabb_v3_precalc(
        &dist_ray_to_aabb_precalc, ss->cache->location, ss->cache->view_normal);
    SculptSearchCircleData data = {
        .ss = ss,
        .sd = sd,
        .radius_squared = SQUARE(ss->cache->radius * radius_scale),
        .original = use_original,
        .dist_ray_to_aabb_precalc = &dist_ray_to_aabb_precalc,
    };
    BKE_pbvh_search_gather(ss->pbvh, sculpt_search_circle_cb, &data, &nodes, r_totnode);
  }
  return nodes;
}

/* Calculate primary direction of movement for many brushes */
static void calc_sculpt_normal(
    Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float r_area_no[3])
{
  const Brush *brush = BKE_paint_brush(&sd->paint);
  const SculptSession *ss = ob->sculpt;

  switch (brush->sculpt_plane) {
    case SCULPT_DISP_DIR_VIEW:
      copy_v3_v3(r_area_no, ss->cache->true_view_normal);
      break;

    case SCULPT_DISP_DIR_X:
      ARRAY_SET_ITEMS(r_area_no, 1, 0, 0);
      break;

    case SCULPT_DISP_DIR_Y:
      ARRAY_SET_ITEMS(r_area_no, 0, 1, 0);
      break;

    case SCULPT_DISP_DIR_Z:
      ARRAY_SET_ITEMS(r_area_no, 0, 0, 1);
      break;

    case SCULPT_DISP_DIR_AREA:
      calc_area_normal(sd, ob, nodes, totnode, r_area_no);
      break;

    default:
      break;
  }
}

static void update_sculpt_normal(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  const Brush *brush = BKE_paint_brush(&sd->paint);
  StrokeCache *cache = ob->sculpt->cache;

  if (cache->mirror_symmetry_pass == 0 && cache->radial_symmetry_pass == 0 &&
      (cache->first_time || !(brush->flag & BRUSH_ORIGINAL_NORMAL))) {
    calc_sculpt_normal(sd, ob, nodes, totnode, cache->sculpt_normal);
    if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
      project_plane_v3_v3v3(cache->sculpt_normal, cache->sculpt_normal, cache->view_normal);
      normalize_v3(cache->sculpt_normal);
    }
    copy_v3_v3(cache->sculpt_normal_symm, cache->sculpt_normal);
  }
  else {
    copy_v3_v3(cache->sculpt_normal_symm, cache->sculpt_normal);
    flip_v3(cache->sculpt_normal_symm, cache->mirror_symmetry_pass);
    mul_m4_v3(cache->symm_rot_mat, cache->sculpt_normal_symm);
  }
}

static void calc_local_y(ViewContext *vc, const float center[3], float y[3])
{
  Object *ob = vc->obact;
  float loc[3], mval_f[2] = {0.0f, 1.0f};
  float zfac;

  mul_v3_m4v3(loc, ob->imat, center);
  zfac = ED_view3d_calc_zfac(vc->rv3d, loc, NULL);

  ED_view3d_win_to_delta(vc->ar, mval_f, y, zfac);
  normalize_v3(y);

  add_v3_v3(y, ob->loc);
  mul_m4_v3(ob->imat, y);
}

static void calc_brush_local_mat(const Brush *brush, Object *ob, float local_mat[4][4])
{
  const StrokeCache *cache = ob->sculpt->cache;
  float tmat[4][4];
  float mat[4][4];
  float scale[4][4];
  float angle, v[3];
  float up[3];

  /* Ensure ob->imat is up to date */
  invert_m4_m4(ob->imat, ob->obmat);

  /* Initialize last column of matrix */
  mat[0][3] = 0;
  mat[1][3] = 0;
  mat[2][3] = 0;
  mat[3][3] = 1;

  /* Get view's up vector in object-space */
  calc_local_y(cache->vc, cache->location, up);

  /* Calculate the X axis of the local matrix */
  cross_v3_v3v3(v, up, cache->sculpt_normal);
  /* Apply rotation (user angle, rake, etc.) to X axis */
  angle = brush->mtex.rot - cache->special_rotation;
  rotate_v3_v3v3fl(mat[0], v, cache->sculpt_normal, angle);

  /* Get other axes */
  cross_v3_v3v3(mat[1], cache->sculpt_normal, mat[0]);
  copy_v3_v3(mat[2], cache->sculpt_normal);

  /* Set location */
  copy_v3_v3(mat[3], cache->location);

  /* Scale by brush radius */
  normalize_m4(mat);
  scale_m4_fl(scale, cache->radius);
  mul_m4_m4m4(tmat, mat, scale);

  /* Return inverse (for converting from modelspace coords to local
   * area coords) */
  invert_m4_m4(local_mat, tmat);
}

static void update_brush_local_mat(Sculpt *sd, Object *ob)
{
  StrokeCache *cache = ob->sculpt->cache;

  if (cache->mirror_symmetry_pass == 0 && cache->radial_symmetry_pass == 0) {
    calc_brush_local_mat(BKE_paint_brush(&sd->paint), ob, cache->brush_local_mat);
  }
}

/* For the smooth brush, uses the neighboring vertices around vert to calculate
 * a smoothed location for vert. Skips corner vertices (used by only one
 * polygon.) */
static void neighbor_average(SculptSession *ss, float avg[3], unsigned vert)
{
  const MeshElemMap *vert_map = &ss->pmap[vert];
  const MVert *mvert = ss->mvert;
  float(*deform_co)[3] = ss->deform_cos;

  /* Don't modify corner vertices */
  if (vert_map->count > 1) {
    int i, total = 0;

    zero_v3(avg);

    for (i = 0; i < vert_map->count; i++) {
      const MPoly *p = &ss->mpoly[vert_map->indices[i]];
      unsigned f_adj_v[2];

      if (poly_get_adj_loops_from_vert(p, ss->mloop, vert, f_adj_v) != -1) {
        int j;
        for (j = 0; j < ARRAY_SIZE(f_adj_v); j += 1) {
          if (vert_map->count != 2 || ss->pmap[f_adj_v[j]].count <= 2) {
            add_v3_v3(avg, deform_co ? deform_co[f_adj_v[j]] : mvert[f_adj_v[j]].co);

            total++;
          }
        }
      }
    }

    if (total > 0) {
      mul_v3_fl(avg, 1.0f / total);
      return;
    }
  }

  copy_v3_v3(avg, deform_co ? deform_co[vert] : mvert[vert].co);
}

/* Similar to neighbor_average(), but returns an averaged mask value
 * instead of coordinate. Also does not restrict based on border or
 * corner vertices. */
static float neighbor_average_mask(SculptSession *ss, unsigned vert)
{
  const float *vmask = ss->vmask;
  float avg = 0;
  int i, total = 0;

  for (i = 0; i < ss->pmap[vert].count; i++) {
    const MPoly *p = &ss->mpoly[ss->pmap[vert].indices[i]];
    unsigned f_adj_v[2];

    if (poly_get_adj_loops_from_vert(p, ss->mloop, vert, f_adj_v) != -1) {
      int j;
      for (j = 0; j < ARRAY_SIZE(f_adj_v); j += 1) {
        avg += vmask[f_adj_v[j]];
        total++;
      }
    }
  }

  if (total > 0) {
    return avg / (float)total;
  }
  else {
    return vmask[vert];
  }
}

/* Same logic as neighbor_average(), but for bmesh rather than mesh */
static void bmesh_neighbor_average(float avg[3], BMVert *v)
{
  /* logic for 3 or more is identical */
  const int vfcount = BM_vert_face_count_at_most(v, 3);

  /* Don't modify corner vertices */
  if (vfcount > 1) {
    BMIter liter;
    BMLoop *l;
    int i, total = 0;

    zero_v3(avg);

    BM_ITER_ELEM (l, &liter, v, BM_LOOPS_OF_VERT) {
      const BMVert *adj_v[2] = {l->prev->v, l->next->v};

      for (i = 0; i < ARRAY_SIZE(adj_v); i++) {
        const BMVert *v_other = adj_v[i];
        if (vfcount != 2 || BM_vert_face_count_at_most(v_other, 2) <= 2) {
          add_v3_v3(avg, v_other->co);
          total++;
        }
      }
    }

    if (total > 0) {
      mul_v3_fl(avg, 1.0f / total);
      return;
    }
  }

  copy_v3_v3(avg, v->co);
}

/* For bmesh: average only the four most aligned (parallel and perpendicular) edges
 * relative to a direction. Naturally converges to a quad-like tessellation. */
static void bmesh_four_neighbor_average(float avg[3], float direction[3], BMVert *v)
{
  /* Logic for 3 or more is identical. */
  const int vfcount = BM_vert_face_count_at_most(v, 3);

  /* Don't modify corner vertices. */
  if (vfcount < 2) {
    copy_v3_v3(avg, v->co);
    return;
  }

  /* Project the direction to the vertex normal and create an additional
   * parallel vector. */
  float dir_a[3], dir_b[3];
  cross_v3_v3v3(dir_a, direction, v->no);
  cross_v3_v3v3(dir_b, dir_a, v->no);

  /* The four vectors which will be used for smoothing.
   * Occasionally less than 4 verts match the requirements in that case
   * use 'v' as fallback. */
  BMVert *pos_a = v;
  BMVert *neg_a = v;
  BMVert *pos_b = v;
  BMVert *neg_b = v;

  float pos_score_a = 0.0f;
  float neg_score_a = 0.0f;
  float pos_score_b = 0.0f;
  float neg_score_b = 0.0f;

  BMIter liter;
  BMLoop *l;

  BM_ITER_ELEM (l, &liter, v, BM_LOOPS_OF_VERT) {
    BMVert *adj_v[2] = {l->prev->v, l->next->v};

    for (int i = 0; i < ARRAY_SIZE(adj_v); i++) {
      BMVert *v_other = adj_v[i];

      if (vfcount != 2 || BM_vert_face_count_at_most(v_other, 2) <= 2) {
        float vec[3];
        sub_v3_v3v3(vec, v_other->co, v->co);
        normalize_v3(vec);

        /* The score is a measure of how orthogonal the edge is. */
        float score = dot_v3v3(vec, dir_a);

        if (score >= pos_score_a) {
          pos_a = v_other;
          pos_score_a = score;
        }
        else if (score < neg_score_a) {
          neg_a = v_other;
          neg_score_a = score;
        }
        /* The same scoring but for the perpendicular direction. */
        score = dot_v3v3(vec, dir_b);

        if (score >= pos_score_b) {
          pos_b = v_other;
          pos_score_b = score;
        }
        else if (score < neg_score_b) {
          neg_b = v_other;
          neg_score_b = score;
        }
      }
    }
  }

  /* Average everything together. */
  zero_v3(avg);
  add_v3_v3(avg, pos_a->co);
  add_v3_v3(avg, neg_a->co);
  add_v3_v3(avg, pos_b->co);
  add_v3_v3(avg, neg_b->co);
  mul_v3_fl(avg, 0.25f);

  /* Preserve volume. */
  float vec[3];
  sub_v3_v3(avg, v->co);
  mul_v3_v3fl(vec, v->no, dot_v3v3(avg, v->no));
  sub_v3_v3(avg, vec);
  add_v3_v3(avg, v->co);
}

/* Same logic as neighbor_average_mask(), but for bmesh rather than mesh */
static float bmesh_neighbor_average_mask(BMVert *v, const int cd_vert_mask_offset)
{
  BMIter liter;
  BMLoop *l;
  float avg = 0;
  int i, total = 0;

  BM_ITER_ELEM (l, &liter, v, BM_LOOPS_OF_VERT) {
    /* skip this vertex */
    const BMVert *adj_v[2] = {l->prev->v, l->next->v};

    for (i = 0; i < ARRAY_SIZE(adj_v); i++) {
      const BMVert *v_other = adj_v[i];
      const float *vmask = BM_ELEM_CD_GET_VOID_P(v_other, cd_vert_mask_offset);
      avg += (*vmask);
      total++;
    }
  }

  if (total > 0) {
    return avg / (float)total;
  }
  else {
    const float *vmask = BM_ELEM_CD_GET_VOID_P(v, cd_vert_mask_offset);
    return (*vmask);
  }
}

/* Note: uses after-struct allocated mem to store actual cache... */
typedef struct SculptDoBrushSmoothGridDataChunk {
  size_t tmpgrid_size;
} SculptDoBrushSmoothGridDataChunk;

typedef struct {
  SculptSession *ss;
  const float *ray_start;
  bool hit;
  float depth;
  bool original;

  struct IsectRayPrecalc isect_precalc;
} SculptRaycastData;

typedef struct {
  const float *ray_start;
  bool hit;
  float depth;
  float edge_length;

  struct IsectRayPrecalc isect_precalc;
} SculptDetailRaycastData;

typedef struct {
  SculptSession *ss;
  const float *ray_start, *ray_normal;
  bool hit;
  float depth;
  float dist_sq_to_ray;
  bool original;
} SculptFindNearestToRayData;

static void do_smooth_brush_mesh_task_cb_ex(void *__restrict userdata,
                                            const int n,
                                            const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  const Brush *brush = data->brush;
  const bool smooth_mask = data->smooth_mask;
  float bstrength = data->strength;

  PBVHVertexIter vd;

  CLAMP(bstrength, 0.0f, 1.0f);

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  smooth_mask ? 0.0f : (vd.mask ? *vd.mask : 0.0f),
                                                  tls->thread_id);
      if (smooth_mask) {
        float val = neighbor_average_mask(ss, vd.vert_indices[vd.i]) - *vd.mask;
        val *= fade * bstrength;
        *vd.mask += val;
        CLAMP(*vd.mask, 0.0f, 1.0f);
      }
      else {
        float avg[3], val[3];

        neighbor_average(ss, avg, vd.vert_indices[vd.i]);
        sub_v3_v3v3(val, avg, vd.co);

        madd_v3_v3v3fl(val, vd.co, val, fade);

        sculpt_clip(sd, ss, vd.co, val);
      }

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_smooth_brush_bmesh_task_cb_ex(void *__restrict userdata,
                                             const int n,
                                             const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  const Brush *brush = data->brush;
  const bool smooth_mask = data->smooth_mask;
  float bstrength = data->strength;

  PBVHVertexIter vd;

  CLAMP(bstrength, 0.0f, 1.0f);

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  smooth_mask ? 0.0f : *vd.mask,
                                                  tls->thread_id);
      if (smooth_mask) {
        float val = bmesh_neighbor_average_mask(vd.bm_vert, vd.cd_vert_mask_offset) - *vd.mask;
        val *= fade * bstrength;
        *vd.mask += val;
        CLAMP(*vd.mask, 0.0f, 1.0f);
      }
      else {
        float avg[3], val[3];

        bmesh_neighbor_average(avg, vd.bm_vert);
        sub_v3_v3v3(val, avg, vd.co);

        madd_v3_v3v3fl(val, vd.co, val, fade);

        sculpt_clip(sd, ss, vd.co, val);
      }

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_topology_rake_bmesh_task_cb_ex(void *__restrict userdata,
                                              const int n,
                                              const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  const Brush *brush = data->brush;

  float direction[3];
  copy_v3_v3(direction, ss->cache->grab_delta_symmetry);

  float tmp[3];
  mul_v3_v3fl(
      tmp, ss->cache->sculpt_normal_symm, dot_v3v3(ss->cache->sculpt_normal_symm, direction));
  sub_v3_v3(direction, tmp);

  /* Cancel if there's no grab data. */
  if (is_zero_v3(direction)) {
    return;
  }

  float bstrength = data->strength;
  CLAMP(bstrength, 0.0f, 1.0f);

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  PBVHVertexIter vd;
  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade =
          bstrength *
          tex_strength(
              ss, brush, vd.co, sqrtf(test.dist), vd.no, vd.fno, *vd.mask, tls->thread_id) *
          ss->cache->pressure;

      float avg[3], val[3];

      bmesh_four_neighbor_average(avg, direction, vd.bm_vert);

      sub_v3_v3v3(val, avg, vd.co);

      madd_v3_v3v3fl(val, vd.co, val, fade);

      sculpt_clip(sd, ss, vd.co, val);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_smooth_brush_multires_task_cb_ex(void *__restrict userdata,
                                                const int n,
                                                const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptDoBrushSmoothGridDataChunk *data_chunk = tls->userdata_chunk;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  const Brush *brush = data->brush;
  const bool smooth_mask = data->smooth_mask;
  float bstrength = data->strength;

  CCGElem **griddata, *gddata;
  CCGKey key;

  float(*tmpgrid_co)[3] = NULL;
  float tmprow_co[2][3];
  float *tmpgrid_mask = NULL;
  float tmprow_mask[2];

  BLI_bitmap *const *grid_hidden;
  int *grid_indices, totgrid, gridsize;
  int i, x, y;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  CLAMP(bstrength, 0.0f, 1.0f);

  BKE_pbvh_node_get_grids(
      ss->pbvh, data->nodes[n], &grid_indices, &totgrid, NULL, &gridsize, &griddata);
  BKE_pbvh_get_grid_key(ss->pbvh, &key);

  grid_hidden = BKE_pbvh_grid_hidden(ss->pbvh);

  if (smooth_mask) {
    tmpgrid_mask = (void *)(data_chunk + 1);
  }
  else {
    tmpgrid_co = (void *)(data_chunk + 1);
  }

  for (i = 0; i < totgrid; i++) {
    int gi = grid_indices[i];
    const BLI_bitmap *gh = grid_hidden[gi];
    gddata = griddata[gi];

    if (smooth_mask) {
      memset(tmpgrid_mask, 0, data_chunk->tmpgrid_size);
    }
    else {
      memset(tmpgrid_co, 0, data_chunk->tmpgrid_size);
    }

    for (y = 0; y < gridsize - 1; y++) {
      const int v = y * gridsize;
      if (smooth_mask) {
        tmprow_mask[0] = (*CCG_elem_offset_mask(&key, gddata, v) +
                          *CCG_elem_offset_mask(&key, gddata, v + gridsize));
      }
      else {
        add_v3_v3v3(tmprow_co[0],
                    CCG_elem_offset_co(&key, gddata, v),
                    CCG_elem_offset_co(&key, gddata, v + gridsize));
      }

      for (x = 0; x < gridsize - 1; x++) {
        const int v1 = x + y * gridsize;
        const int v2 = v1 + 1;
        const int v3 = v1 + gridsize;
        const int v4 = v3 + 1;

        if (smooth_mask) {
          float tmp;

          tmprow_mask[(x + 1) % 2] = (*CCG_elem_offset_mask(&key, gddata, v2) +
                                      *CCG_elem_offset_mask(&key, gddata, v4));
          tmp = tmprow_mask[(x + 1) % 2] + tmprow_mask[x % 2];

          tmpgrid_mask[v1] += tmp;
          tmpgrid_mask[v2] += tmp;
          tmpgrid_mask[v3] += tmp;
          tmpgrid_mask[v4] += tmp;
        }
        else {
          float tmp[3];

          add_v3_v3v3(tmprow_co[(x + 1) % 2],
                      CCG_elem_offset_co(&key, gddata, v2),
                      CCG_elem_offset_co(&key, gddata, v4));
          add_v3_v3v3(tmp, tmprow_co[(x + 1) % 2], tmprow_co[x % 2]);

          add_v3_v3(tmpgrid_co[v1], tmp);
          add_v3_v3(tmpgrid_co[v2], tmp);
          add_v3_v3(tmpgrid_co[v3], tmp);
          add_v3_v3(tmpgrid_co[v4], tmp);
        }
      }
    }

    /* blend with existing coordinates */
    for (y = 0; y < gridsize; y++) {
      for (x = 0; x < gridsize; x++) {
        float *co;
        const float *fno;
        float *mask;
        const int index = y * gridsize + x;

        if (gh) {
          if (BLI_BITMAP_TEST(gh, index)) {
            continue;
          }
        }

        co = CCG_elem_offset_co(&key, gddata, index);
        fno = CCG_elem_offset_no(&key, gddata, index);
        mask = CCG_elem_offset_mask(&key, gddata, index);

        if (sculpt_brush_test_sq_fn(&test, co)) {
          const float strength_mask = (smooth_mask ? 0.0f : *mask);
          const float fade =
              bstrength *
              tex_strength(
                  ss, brush, co, sqrtf(test.dist), NULL, fno, strength_mask, tls->thread_id);
          float f = 1.0f / 16.0f;

          if (x == 0 || x == gridsize - 1) {
            f *= 2.0f;
          }

          if (y == 0 || y == gridsize - 1) {
            f *= 2.0f;
          }

          if (smooth_mask) {
            *mask += ((tmpgrid_mask[index] * f) - *mask) * fade;
          }
          else {
            float *avg = tmpgrid_co[index];
            float val[3];

            mul_v3_fl(avg, f);
            sub_v3_v3v3(val, avg, co);
            madd_v3_v3v3fl(val, co, val, fade);

            sculpt_clip(sd, ss, co, val);
          }
        }
      }
    }
  }
}

static void smooth(Sculpt *sd,
                   Object *ob,
                   PBVHNode **nodes,
                   const int totnode,
                   float bstrength,
                   const bool smooth_mask)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const int max_iterations = 4;
  const float fract = 1.0f / max_iterations;
  PBVHType type = BKE_pbvh_type(ss->pbvh);
  int iteration, count;
  float last;

  CLAMP(bstrength, 0.0f, 1.0f);

  count = (int)(bstrength * max_iterations);
  last = max_iterations * (bstrength - count * fract);

  if (type == PBVH_FACES && !ss->pmap) {
    BLI_assert(!"sculpt smooth: pmap missing");
    return;
  }

  for (iteration = 0; iteration <= count; ++iteration) {
    const float strength = (iteration != count) ? 1.0f : last;

    SculptThreadedTaskData data = {
        .sd = sd,
        .ob = ob,
        .brush = brush,
        .nodes = nodes,
        .smooth_mask = smooth_mask,
        .strength = strength,
    };

    ParallelRangeSettings settings;
    BLI_parallel_range_settings_defaults(&settings);
    settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);

    switch (type) {
      case PBVH_GRIDS: {
        int gridsize;
        size_t size;
        SculptDoBrushSmoothGridDataChunk *data_chunk;

        BKE_pbvh_node_get_grids(ss->pbvh, NULL, NULL, NULL, NULL, &gridsize, NULL);
        size = (size_t)gridsize;
        size = sizeof(float) * size * size * (smooth_mask ? 1 : 3);
        data_chunk = MEM_mallocN(sizeof(*data_chunk) + size, __func__);
        data_chunk->tmpgrid_size = size;
        size += sizeof(*data_chunk);

        settings.userdata_chunk = data_chunk;
        settings.userdata_chunk_size = size;
        BLI_task_parallel_range(0, totnode, &data, do_smooth_brush_multires_task_cb_ex, &settings);

        MEM_freeN(data_chunk);
        break;
      }
      case PBVH_FACES:
        BLI_task_parallel_range(0, totnode, &data, do_smooth_brush_mesh_task_cb_ex, &settings);
        break;
      case PBVH_BMESH:
        BLI_task_parallel_range(0, totnode, &data, do_smooth_brush_bmesh_task_cb_ex, &settings);
        break;
    }

    if (ss->multires) {
      multires_stitch_grids(ob);
    }
  }
}

static void bmesh_topology_rake(
    Sculpt *sd, Object *ob, PBVHNode **nodes, const int totnode, float bstrength)
{
  Brush *brush = BKE_paint_brush(&sd->paint);
  CLAMP(bstrength, 0.0f, 1.0f);

  /* Interactions increase both strength and quality. */
  const int iterations = 3;

  int iteration;
  const int count = iterations * bstrength + 1;
  const float factor = iterations * bstrength / count;

  for (iteration = 0; iteration <= count; ++iteration) {

    SculptThreadedTaskData data = {
        .sd = sd,
        .ob = ob,
        .brush = brush,
        .nodes = nodes,
        .strength = factor,
    };
    ParallelRangeSettings settings;
    BLI_parallel_range_settings_defaults(&settings);
    settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);

    BLI_task_parallel_range(0, totnode, &data, do_topology_rake_bmesh_task_cb_ex, &settings);
  }
}

static void do_smooth_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  smooth(sd, ob, nodes, totnode, ss->cache->bstrength, false);
}

static void do_mask_brush_draw_task_cb_ex(void *__restrict userdata,
                                          const int n,
                                          const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float bstrength = ss->cache->bstrength;

  PBVHVertexIter vd;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = tex_strength(
          ss, brush, vd.co, sqrtf(test.dist), vd.no, vd.fno, 0.0f, tls->thread_id);

      (*vd.mask) += fade * bstrength;
      CLAMP(*vd.mask, 0, 1);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
    BKE_pbvh_vertex_iter_end;
  }
}

static void do_mask_brush_draw(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  Brush *brush = BKE_paint_brush(&sd->paint);

  /* threaded loop over nodes */
  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_mask_brush_draw_task_cb_ex, &settings);
}

static void do_mask_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  switch ((BrushMaskTool)brush->mask_tool) {
    case BRUSH_MASK_DRAW:
      do_mask_brush_draw(sd, ob, nodes, totnode);
      break;
    case BRUSH_MASK_SMOOTH:
      smooth(sd, ob, nodes, totnode, ss->cache->bstrength, true);
      break;
  }
}

static void do_draw_brush_task_cb_ex(void *__restrict userdata,
                                     const int n,
                                     const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *offset = data->offset;

  PBVHVertexIter vd;
  float(*proxy)[3];

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      /* offset vertex */
      const float fade = tex_strength(ss,
                                      brush,
                                      vd.co,
                                      sqrtf(test.dist),
                                      vd.no,
                                      vd.fno,
                                      vd.mask ? *vd.mask : 0.0f,
                                      tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], offset, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_draw_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float offset[3];
  const float bstrength = ss->cache->bstrength;

  /* offset with as much as possible factored in already */
  mul_v3_v3fl(offset, ss->cache->sculpt_normal_symm, ss->cache->radius);
  mul_v3_v3(offset, ss->cache->scale);
  mul_v3_fl(offset, bstrength);

  /* XXX - this shouldn't be necessary, but sculpting crashes in blender2.8 otherwise
   * initialize before threads so they can do curve mapping */
  curvemapping_initialize(brush->curve);

  /* threaded loop over nodes */
  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .offset = offset,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_draw_brush_task_cb_ex, &settings);
}

/**
 * Used for 'SCULPT_TOOL_CREASE' and 'SCULPT_TOOL_BLOB'
 */
static void do_crease_brush_task_cb_ex(void *__restrict userdata,
                                       const int n,
                                       const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  SculptProjectVector *spvc = data->spvc;
  const float flippedbstrength = data->flippedbstrength;
  const float *offset = data->offset;

  PBVHVertexIter vd;
  float(*proxy)[3];

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      /* offset vertex */
      const float fade = tex_strength(ss,
                                      brush,
                                      vd.co,
                                      sqrtf(test.dist),
                                      vd.no,
                                      vd.fno,
                                      vd.mask ? *vd.mask : 0.0f,
                                      tls->thread_id);
      float val1[3];
      float val2[3];

      /* first we pinch */
      sub_v3_v3v3(val1, test.location, vd.co);
      if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
        project_plane_v3_v3v3(val1, val1, ss->cache->view_normal);
      }

      mul_v3_fl(val1, fade * flippedbstrength);

      sculpt_project_v3(spvc, val1, val1);

      /* then we draw */
      mul_v3_v3fl(val2, offset, fade);

      add_v3_v3v3(proxy[vd.i], val1, val2);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_crease_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  const Scene *scene = ss->cache->vc->scene;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float offset[3];
  float bstrength = ss->cache->bstrength;
  float flippedbstrength, crease_correction;
  float brush_alpha;

  SculptProjectVector spvc;

  /* offset with as much as possible factored in already */
  mul_v3_v3fl(offset, ss->cache->sculpt_normal_symm, ss->cache->radius);
  mul_v3_v3(offset, ss->cache->scale);
  mul_v3_fl(offset, bstrength);

  /* We divide out the squared alpha and multiply by the squared crease
   * to give us the pinch strength. */
  crease_correction = brush->crease_pinch_factor * brush->crease_pinch_factor;
  brush_alpha = BKE_brush_alpha_get(scene, brush);
  if (brush_alpha > 0.0f) {
    crease_correction /= brush_alpha * brush_alpha;
  }

  /* we always want crease to pinch or blob to relax even when draw is negative */
  flippedbstrength = (bstrength < 0) ? -crease_correction * bstrength :
                                       crease_correction * bstrength;

  if (brush->sculpt_tool == SCULPT_TOOL_BLOB) {
    flippedbstrength *= -1.0f;
  }

  /* Use surface normal for 'spvc',
   * so the vertices are pinched towards a line instead of a single point.
   * Without this we get a 'flat' surface surrounding the pinch */
  sculpt_project_v3_cache_init(&spvc, ss->cache->sculpt_normal_symm);

  /* threaded loop over nodes */
  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .spvc = &spvc,
      .offset = offset,
      .flippedbstrength = flippedbstrength,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_crease_brush_task_cb_ex, &settings);
}

static void do_pinch_brush_task_cb_ex(void *__restrict userdata,
                                      const int n,
                                      const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);
      float val[3];

      sub_v3_v3v3(val, test.location, vd.co);
      if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
        project_plane_v3_v3v3(val, val, ss->cache->view_normal);
      }
      mul_v3_v3fl(proxy[vd.i], val, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_pinch_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  Brush *brush = BKE_paint_brush(&sd->paint);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_pinch_brush_task_cb_ex, &settings);
}

static void do_grab_brush_task_cb_ex(void *__restrict userdata,
                                     const int n,
                                     const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *grab_delta = data->grab_delta;

  PBVHVertexIter vd;
  SculptOrigVertData orig_data;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  sculpt_orig_vert_data_init(&orig_data, data->ob, data->nodes[n]);

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    sculpt_orig_vert_data_update(&orig_data, &vd);

    if (sculpt_brush_test_sq_fn(&test, orig_data.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  orig_data.co,
                                                  sqrtf(test.dist),
                                                  orig_data.no,
                                                  NULL,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], grab_delta, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_grab_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float grab_delta[3];

  copy_v3_v3(grab_delta, ss->cache->grab_delta_symmetry);

  if (ss->cache->normal_weight > 0.0f) {
    sculpt_project_v3_normal_align(ss, ss->cache->normal_weight, grab_delta);
  }

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .grab_delta = grab_delta,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_grab_brush_task_cb_ex, &settings);
}

static void do_nudge_brush_task_cb_ex(void *__restrict userdata,
                                      const int n,
                                      const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *cono = data->cono;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], cono, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_nudge_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float grab_delta[3];
  float tmp[3], cono[3];

  copy_v3_v3(grab_delta, ss->cache->grab_delta_symmetry);

  cross_v3_v3v3(tmp, ss->cache->sculpt_normal_symm, grab_delta);
  cross_v3_v3v3(cono, tmp, ss->cache->sculpt_normal_symm);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .cono = cono,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_nudge_brush_task_cb_ex, &settings);
}

static void do_snake_hook_brush_task_cb_ex(void *__restrict userdata,
                                           const int n,
                                           const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  SculptProjectVector *spvc = data->spvc;
  const float *grab_delta = data->grab_delta;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;
  const bool do_rake_rotation = ss->cache->is_rake_rotation_valid;
  const bool do_pinch = (brush->crease_pinch_factor != 0.5f);
  const float pinch = do_pinch ? (2.0f * (0.5f - brush->crease_pinch_factor) *
                                  (len_v3(grab_delta) / ss->cache->radius)) :
                                 0.0f;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], grab_delta, fade);

      /* negative pinch will inflate, helps maintain volume */
      if (do_pinch) {
        float delta_pinch_init[3], delta_pinch[3];

        sub_v3_v3v3(delta_pinch, vd.co, test.location);
        if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
          project_plane_v3_v3v3(delta_pinch, delta_pinch, ss->cache->true_view_normal);
        }

        /* important to calculate based on the grabbed location
         * (intentionally ignore fade here). */
        add_v3_v3(delta_pinch, grab_delta);

        sculpt_project_v3(spvc, delta_pinch, delta_pinch);

        copy_v3_v3(delta_pinch_init, delta_pinch);

        float pinch_fade = pinch * fade;
        /* when reducing, scale reduction back by how close to the center we are,
         * so we don't pinch into nothingness */
        if (pinch > 0.0f) {
          /* square to have even less impact for close vertices */
          pinch_fade *= pow2f(min_ff(1.0f, len_v3(delta_pinch) / ss->cache->radius));
        }
        mul_v3_fl(delta_pinch, 1.0f + pinch_fade);
        sub_v3_v3v3(delta_pinch, delta_pinch_init, delta_pinch);
        add_v3_v3(proxy[vd.i], delta_pinch);
      }

      if (do_rake_rotation) {
        float delta_rotate[3];
        sculpt_rake_rotate(ss, test.location, vd.co, fade, delta_rotate);
        add_v3_v3(proxy[vd.i], delta_rotate);
      }

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_snake_hook_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  const float bstrength = ss->cache->bstrength;
  float grab_delta[3];

  SculptProjectVector spvc;

  copy_v3_v3(grab_delta, ss->cache->grab_delta_symmetry);

  if (bstrength < 0) {
    negate_v3(grab_delta);
  }

  if (ss->cache->normal_weight > 0.0f) {
    sculpt_project_v3_normal_align(ss, ss->cache->normal_weight, grab_delta);
  }

  /* optionally pinch while painting */
  if (brush->crease_pinch_factor != 0.5f) {
    sculpt_project_v3_cache_init(&spvc, grab_delta);
  }

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .spvc = &spvc,
      .grab_delta = grab_delta,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_snake_hook_brush_task_cb_ex, &settings);
}

static void do_thumb_brush_task_cb_ex(void *__restrict userdata,
                                      const int n,
                                      const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *cono = data->cono;

  PBVHVertexIter vd;
  SculptOrigVertData orig_data;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  sculpt_orig_vert_data_init(&orig_data, data->ob, data->nodes[n]);

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    sculpt_orig_vert_data_update(&orig_data, &vd);

    if (sculpt_brush_test_sq_fn(&test, orig_data.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  orig_data.co,
                                                  sqrtf(test.dist),
                                                  orig_data.no,
                                                  NULL,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], cono, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_thumb_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float grab_delta[3];
  float tmp[3], cono[3];

  copy_v3_v3(grab_delta, ss->cache->grab_delta_symmetry);

  cross_v3_v3v3(tmp, ss->cache->sculpt_normal_symm, grab_delta);
  cross_v3_v3v3(cono, tmp, ss->cache->sculpt_normal_symm);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .cono = cono,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_thumb_brush_task_cb_ex, &settings);
}

static void do_rotate_brush_task_cb_ex(void *__restrict userdata,
                                       const int n,
                                       const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float angle = data->angle;

  PBVHVertexIter vd;
  SculptOrigVertData orig_data;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  sculpt_orig_vert_data_init(&orig_data, data->ob, data->nodes[n]);

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    sculpt_orig_vert_data_update(&orig_data, &vd);

    if (sculpt_brush_test_sq_fn(&test, orig_data.co)) {
      float vec[3], rot[3][3];
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  orig_data.co,
                                                  sqrtf(test.dist),
                                                  orig_data.no,
                                                  NULL,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);

      sub_v3_v3v3(vec, orig_data.co, ss->cache->location);
      axis_angle_normalized_to_mat3(rot, ss->cache->sculpt_normal_symm, angle * fade);
      mul_v3_m3v3(proxy[vd.i], rot, vec);
      add_v3_v3(proxy[vd.i], ss->cache->location);
      sub_v3_v3(proxy[vd.i], orig_data.co);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_rotate_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  static const int flip[8] = {1, -1, -1, 1, -1, 1, 1, -1};
  const float angle = ss->cache->vertex_rotation * flip[ss->cache->mirror_symmetry_pass];

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .angle = angle,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_rotate_brush_task_cb_ex, &settings);
}

static void do_layer_brush_task_cb_ex(void *__restrict userdata,
                                      const int n,
                                      const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  const Brush *brush = data->brush;
  const float *offset = data->offset;

  PBVHVertexIter vd;
  SculptOrigVertData orig_data;
  float *layer_disp;
  const float bstrength = ss->cache->bstrength;
  const float lim = (bstrength < 0) ? -data->brush->height : data->brush->height;
  /* XXX: layer brush needs conversion to proxy but its more complicated */
  /* proxy = BKE_pbvh_node_add_proxy(ss->pbvh, nodes[n])->co; */

  sculpt_orig_vert_data_init(&orig_data, data->ob, data->nodes[n]);

  /* Why does this have to be thread-protected? */
  BLI_mutex_lock(&data->mutex);
  layer_disp = BKE_pbvh_node_layer_disp_get(ss->pbvh, data->nodes[n]);
  BLI_mutex_unlock(&data->mutex);

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    sculpt_orig_vert_data_update(&orig_data, &vd);

    if (sculpt_brush_test_sq_fn(&test, orig_data.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);
      float *disp = &layer_disp[vd.i];
      float val[3];

      *disp += fade;

      /* Don't let the displacement go past the limit */
      if ((lim < 0.0f && *disp < lim) || (lim >= 0.0f && *disp > lim)) {
        *disp = lim;
      }

      mul_v3_v3fl(val, offset, *disp);

      if (!ss->multires && !ss->bm && ss->layer_co && (brush->flag & BRUSH_PERSISTENT)) {
        int index = vd.vert_indices[vd.i];

        /* persistent base */
        add_v3_v3(val, ss->layer_co[index]);
      }
      else {
        add_v3_v3(val, orig_data.co);
      }

      sculpt_clip(sd, ss, vd.co, val);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_layer_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  float offset[3];

  mul_v3_v3v3(offset, ss->cache->scale, ss->cache->sculpt_normal_symm);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .offset = offset,
  };
  BLI_mutex_init(&data.mutex);

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_layer_brush_task_cb_ex, &settings);

  BLI_mutex_end(&data.mutex);
}

static void do_inflate_brush_task_cb_ex(void *__restrict userdata,
                                        const int n,
                                        const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = bstrength * tex_strength(ss,
                                                  brush,
                                                  vd.co,
                                                  sqrtf(test.dist),
                                                  vd.no,
                                                  vd.fno,
                                                  vd.mask ? *vd.mask : 0.0f,
                                                  tls->thread_id);
      float val[3];

      if (vd.fno) {
        copy_v3_v3(val, vd.fno);
      }
      else {
        normal_short_to_float_v3(val, vd.no);
      }

      mul_v3_fl(val, fade * ss->cache->radius);
      mul_v3_v3v3(proxy[vd.i], val, ss->cache->scale);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_inflate_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  Brush *brush = BKE_paint_brush(&sd->paint);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_inflate_brush_task_cb_ex, &settings);
}

static void calc_sculpt_plane(
    Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float r_area_no[3], float r_area_co[3])
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  if (ss->cache->mirror_symmetry_pass == 0 && ss->cache->radial_symmetry_pass == 0 &&
      ss->cache->tile_pass == 0 &&
      (ss->cache->first_time || !(brush->flag & BRUSH_ORIGINAL_NORMAL))) {
    switch (brush->sculpt_plane) {
      case SCULPT_DISP_DIR_VIEW:
        copy_v3_v3(r_area_no, ss->cache->true_view_normal);
        break;

      case SCULPT_DISP_DIR_X:
        ARRAY_SET_ITEMS(r_area_no, 1, 0, 0);
        break;

      case SCULPT_DISP_DIR_Y:
        ARRAY_SET_ITEMS(r_area_no, 0, 1, 0);
        break;

      case SCULPT_DISP_DIR_Z:
        ARRAY_SET_ITEMS(r_area_no, 0, 0, 1);
        break;

      case SCULPT_DISP_DIR_AREA:
        calc_area_normal_and_center(sd, ob, nodes, totnode, r_area_no, r_area_co);
        if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
          project_plane_v3_v3v3(r_area_no, r_area_no, ss->cache->view_normal);
          normalize_v3(r_area_no);
        }
        break;

      default:
        break;
    }

    /* for flatten center */
    /* flatten center has not been calculated yet if we are not using the area normal */
    if (brush->sculpt_plane != SCULPT_DISP_DIR_AREA) {
      calc_area_center(sd, ob, nodes, totnode, r_area_co);
    }

    /* for area normal */
    copy_v3_v3(ss->cache->sculpt_normal, r_area_no);

    /* for flatten center */
    copy_v3_v3(ss->cache->last_center, r_area_co);
  }
  else {
    /* for area normal */
    copy_v3_v3(r_area_no, ss->cache->sculpt_normal);

    /* for flatten center */
    copy_v3_v3(r_area_co, ss->cache->last_center);

    /* for area normal */
    flip_v3(r_area_no, ss->cache->mirror_symmetry_pass);

    /* for flatten center */
    flip_v3(r_area_co, ss->cache->mirror_symmetry_pass);

    /* for area normal */
    mul_m4_v3(ss->cache->symm_rot_mat, r_area_no);

    /* for flatten center */
    mul_m4_v3(ss->cache->symm_rot_mat, r_area_co);

    /* shift the plane for the current tile */
    add_v3_v3(r_area_co, ss->cache->plane_offset);
  }
}

static int plane_trim(const StrokeCache *cache, const Brush *brush, const float val[3])
{
  return (!(brush->flag & BRUSH_PLANE_TRIM) ||
          ((dot_v3v3(val, val) <= cache->radius_squared * cache->plane_trim_squared)));
}

static bool plane_point_side_flip(const float co[3], const float plane[4], const bool flip)
{
  float d = plane_point_side_v3(plane, co);
  if (flip) {
    d = -d;
  }
  return d <= 0.0f;
}

static int plane_point_side(const float co[3], const float plane[4])
{
  float d = plane_point_side_v3(plane, co);
  return d <= 0.0f;
}

static float get_offset(Sculpt *sd, SculptSession *ss)
{
  Brush *brush = BKE_paint_brush(&sd->paint);

  float rv = brush->plane_offset;

  if (brush->flag & BRUSH_OFFSET_PRESSURE) {
    rv *= ss->cache->pressure;
  }

  return rv;
}

static void do_flatten_brush_task_cb_ex(void *__restrict userdata,
                                        const int n,
                                        const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *area_no = data->area_no;
  const float *area_co = data->area_co;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  plane_from_point_normal_v3(test.plane_tool, area_co, area_no);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      float intr[3];
      float val[3];

      closest_to_plane_normalized_v3(intr, test.plane_tool, vd.co);

      sub_v3_v3v3(val, intr, vd.co);

      if (plane_trim(ss->cache, brush, val)) {
        const float fade = bstrength * tex_strength(ss,
                                                    brush,
                                                    vd.co,
                                                    sqrtf(test.dist),
                                                    vd.no,
                                                    vd.fno,
                                                    vd.mask ? *vd.mask : 0.0f,
                                                    tls->thread_id);

        mul_v3_v3fl(proxy[vd.i], val, fade);

        if (vd.mvert) {
          vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
        }
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_flatten_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const float radius = ss->cache->radius;

  float area_no[3];
  float area_co[3];

  float offset = get_offset(sd, ss);
  float displace;
  float temp[3];

  calc_sculpt_plane(sd, ob, nodes, totnode, area_no, area_co);

  displace = radius * offset;

  mul_v3_v3v3(temp, area_no, ss->cache->scale);
  mul_v3_fl(temp, displace);
  add_v3_v3(area_co, temp);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .area_no = area_no,
      .area_co = area_co,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_flatten_brush_task_cb_ex, &settings);
}

static void do_clay_brush_task_cb_ex(void *__restrict userdata,
                                     const int n,
                                     const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *area_no = data->area_no;
  const float *area_co = data->area_co;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const bool flip = (ss->cache->bstrength < 0);
  const float bstrength = flip ? -ss->cache->bstrength : ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  plane_from_point_normal_v3(test.plane_tool, area_co, area_no);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      if (plane_point_side_flip(vd.co, test.plane_tool, flip)) {
        float intr[3];
        float val[3];

        closest_to_plane_normalized_v3(intr, test.plane_tool, vd.co);

        sub_v3_v3v3(val, intr, vd.co);

        if (plane_trim(ss->cache, brush, val)) {
          /* note, the normal from the vertices is ignored,
           * causes glitch with planes, see: T44390 */
          const float fade = bstrength * tex_strength(ss,
                                                      brush,
                                                      vd.co,
                                                      sqrtf(test.dist),
                                                      vd.no,
                                                      vd.fno,
                                                      vd.mask ? *vd.mask : 0.0f,
                                                      tls->thread_id);

          mul_v3_v3fl(proxy[vd.i], val, fade);

          if (vd.mvert) {
            vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
          }
        }
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_clay_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const bool flip = (ss->cache->bstrength < 0);
  const float radius = flip ? -ss->cache->radius : ss->cache->radius;

  float offset = get_offset(sd, ss);
  float displace;

  float area_no[3];
  float area_co[3];
  float temp[3];

  calc_sculpt_plane(sd, ob, nodes, totnode, area_no, area_co);

  displace = radius * (0.25f + offset);

  mul_v3_v3v3(temp, area_no, ss->cache->scale);
  mul_v3_fl(temp, displace);
  add_v3_v3(area_co, temp);

  /* add_v3_v3v3(p, ss->cache->location, area_no); */

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .area_no = area_no,
      .area_co = area_co,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_clay_brush_task_cb_ex, &settings);
}

static void do_clay_strips_brush_task_cb_ex(void *__restrict userdata,
                                            const int n,
                                            const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  float(*mat)[4] = data->mat;
  const float *area_no_sp = data->area_no_sp;
  const float *area_co = data->area_co;

  PBVHVertexIter vd;
  SculptBrushTest test;
  float(*proxy)[3];
  const bool flip = (ss->cache->bstrength < 0);
  const float bstrength = flip ? -ss->cache->bstrength : ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  sculpt_brush_test_init(ss, &test);
  plane_from_point_normal_v3(test.plane_tool, area_co, area_no_sp);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_cube(&test, vd.co, mat)) {
      if (plane_point_side_flip(vd.co, test.plane_tool, flip)) {
        float intr[3];
        float val[3];

        closest_to_plane_normalized_v3(intr, test.plane_tool, vd.co);

        sub_v3_v3v3(val, intr, vd.co);

        if (plane_trim(ss->cache, brush, val)) {
          /* note, the normal from the vertices is ignored,
           * causes glitch with planes, see: T44390 */
          const float fade = bstrength * tex_strength(ss,
                                                      brush,
                                                      vd.co,
                                                      ss->cache->radius * test.dist,
                                                      vd.no,
                                                      vd.fno,
                                                      vd.mask ? *vd.mask : 0.0f,
                                                      tls->thread_id);

          mul_v3_v3fl(proxy[vd.i], val, fade);

          if (vd.mvert) {
            vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
          }
        }
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_clay_strips_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const bool flip = (ss->cache->bstrength < 0);
  const float radius = flip ? -ss->cache->radius : ss->cache->radius;
  const float offset = get_offset(sd, ss);
  const float displace = radius * (0.25f + offset);

  float area_no_sp[3]; /* the sculpt-plane normal (whatever its set to) */
  float area_no[3];    /* geometry normal */
  float area_co[3];

  float temp[3];
  float mat[4][4];
  float scale[4][4];
  float tmat[4][4];

  calc_sculpt_plane(sd, ob, nodes, totnode, area_no_sp, area_co);

  if (brush->sculpt_plane != SCULPT_DISP_DIR_AREA || (brush->flag & BRUSH_ORIGINAL_NORMAL)) {
    calc_area_normal(sd, ob, nodes, totnode, area_no);
  }
  else {
    copy_v3_v3(area_no, area_no_sp);
  }

  /* delay the first daub because grab delta is not setup */
  if (ss->cache->first_time) {
    return;
  }

  if (is_zero_v3(ss->cache->grab_delta_symmetry)) {
    return;
  }

  mul_v3_v3v3(temp, area_no_sp, ss->cache->scale);
  mul_v3_fl(temp, displace);
  add_v3_v3(area_co, temp);

  /* init mat */
  cross_v3_v3v3(mat[0], area_no, ss->cache->grab_delta_symmetry);
  mat[0][3] = 0;
  cross_v3_v3v3(mat[1], area_no, mat[0]);
  mat[1][3] = 0;
  copy_v3_v3(mat[2], area_no);
  mat[2][3] = 0;
  copy_v3_v3(mat[3], ss->cache->location);
  mat[3][3] = 1;
  normalize_m4(mat);

  /* scale mat */
  scale_m4_fl(scale, ss->cache->radius);
  mul_m4_m4m4(tmat, mat, scale);
  invert_m4_m4(mat, tmat);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .area_no_sp = area_no_sp,
      .area_co = area_co,
      .mat = mat,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_clay_strips_brush_task_cb_ex, &settings);
}

static void do_fill_brush_task_cb_ex(void *__restrict userdata,
                                     const int n,
                                     const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *area_no = data->area_no;
  const float *area_co = data->area_co;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  plane_from_point_normal_v3(test.plane_tool, area_co, area_no);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      if (plane_point_side(vd.co, test.plane_tool)) {
        float intr[3];
        float val[3];

        closest_to_plane_normalized_v3(intr, test.plane_tool, vd.co);

        sub_v3_v3v3(val, intr, vd.co);

        if (plane_trim(ss->cache, brush, val)) {
          const float fade = bstrength * tex_strength(ss,
                                                      brush,
                                                      vd.co,
                                                      sqrtf(test.dist),
                                                      vd.no,
                                                      vd.fno,
                                                      vd.mask ? *vd.mask : 0.0f,
                                                      tls->thread_id);

          mul_v3_v3fl(proxy[vd.i], val, fade);

          if (vd.mvert) {
            vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
          }
        }
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_fill_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const float radius = ss->cache->radius;

  float area_no[3];
  float area_co[3];
  float offset = get_offset(sd, ss);

  float displace;

  float temp[3];

  calc_sculpt_plane(sd, ob, nodes, totnode, area_no, area_co);

  displace = radius * offset;

  mul_v3_v3v3(temp, area_no, ss->cache->scale);
  mul_v3_fl(temp, displace);
  add_v3_v3(area_co, temp);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .area_no = area_no,
      .area_co = area_co,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_fill_brush_task_cb_ex, &settings);
}

static void do_scrape_brush_task_cb_ex(void *__restrict userdata,
                                       const int n,
                                       const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  const float *area_no = data->area_no;
  const float *area_co = data->area_co;

  PBVHVertexIter vd;
  float(*proxy)[3];
  const float bstrength = ss->cache->bstrength;

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);
  plane_from_point_normal_v3(test.plane_tool, area_co, area_no);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      if (!plane_point_side(vd.co, test.plane_tool)) {
        float intr[3];
        float val[3];

        closest_to_plane_normalized_v3(intr, test.plane_tool, vd.co);

        sub_v3_v3v3(val, intr, vd.co);

        if (plane_trim(ss->cache, brush, val)) {
          const float fade = bstrength * tex_strength(ss,
                                                      brush,
                                                      vd.co,
                                                      sqrtf(test.dist),
                                                      vd.no,
                                                      vd.fno,
                                                      vd.mask ? *vd.mask : 0.0f,
                                                      tls->thread_id);

          mul_v3_v3fl(proxy[vd.i], val, fade);

          if (vd.mvert) {
            vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
          }
        }
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_scrape_brush(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  const float radius = ss->cache->radius;

  float area_no[3];
  float area_co[3];
  float offset = get_offset(sd, ss);

  float displace;

  float temp[3];

  calc_sculpt_plane(sd, ob, nodes, totnode, area_no, area_co);

  displace = -radius * offset;

  mul_v3_v3v3(temp, area_no, ss->cache->scale);
  mul_v3_fl(temp, displace);
  add_v3_v3(area_co, temp);

  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .area_no = area_no,
      .area_co = area_co,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_scrape_brush_task_cb_ex, &settings);
}

static void do_gravity_task_cb_ex(void *__restrict userdata,
                                  const int n,
                                  const ParallelRangeTLS *__restrict tls)
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  const Brush *brush = data->brush;
  float *offset = data->offset;

  PBVHVertexIter vd;
  float(*proxy)[3];

  proxy = BKE_pbvh_node_add_proxy(ss->pbvh, data->nodes[n])->co;

  SculptBrushTest test;
  SculptBrushTestFn sculpt_brush_test_sq_fn = sculpt_brush_test_init_with_falloff_shape(
      ss, &test, data->brush->falloff_shape);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    if (sculpt_brush_test_sq_fn(&test, vd.co)) {
      const float fade = tex_strength(ss,
                                      brush,
                                      vd.co,
                                      sqrtf(test.dist),
                                      vd.no,
                                      vd.fno,
                                      vd.mask ? *vd.mask : 0.0f,
                                      tls->thread_id);

      mul_v3_v3fl(proxy[vd.i], offset, fade);

      if (vd.mvert) {
        vd.mvert->flag |= ME_VERT_PBVH_UPDATE;
      }
    }
  }
  BKE_pbvh_vertex_iter_end;
}

static void do_gravity(Sculpt *sd, Object *ob, PBVHNode **nodes, int totnode, float bstrength)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  float offset[3] /*, area_no[3]*/;
  float gravity_vector[3];

  mul_v3_v3fl(gravity_vector, ss->cache->gravity_direction, -ss->cache->radius_squared);

  /* offset with as much as possible factored in already */
  mul_v3_v3v3(offset, gravity_vector, ss->cache->scale);
  mul_v3_fl(offset, bstrength);

  /* threaded loop over nodes */
  SculptThreadedTaskData data = {
      .sd = sd,
      .ob = ob,
      .brush = brush,
      .nodes = nodes,
      .offset = offset,
  };

  ParallelRangeSettings settings;
  BLI_parallel_range_settings_defaults(&settings);
  settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
  BLI_task_parallel_range(0, totnode, &data, do_gravity_task_cb_ex, &settings);
}

void sculpt_vertcos_to_key(Object *ob, KeyBlock *kb, float (*vertCos)[3])
{
  Mesh *me = (Mesh *)ob->data;
  float(*ofs)[3] = NULL;
  int a;
  const int kb_act_idx = ob->shapenr - 1;
  KeyBlock *currkey;

  /* for relative keys editing of base should update other keys */
  if (BKE_keyblock_is_basis(me->key, kb_act_idx)) {
    ofs = BKE_keyblock_convert_to_vertcos(ob, kb);

    /* calculate key coord offsets (from previous location) */
    for (a = 0; a < me->totvert; a++) {
      sub_v3_v3v3(ofs[a], vertCos[a], ofs[a]);
    }

    /* apply offsets on other keys */
    for (currkey = me->key->block.first; currkey; currkey = currkey->next) {
      if ((currkey != kb) && (currkey->relative == kb_act_idx)) {
        BKE_keyblock_update_from_offset(ob, currkey, ofs);
      }
    }

    MEM_freeN(ofs);
  }

  /* modifying of basis key should update mesh */
  if (kb == me->key->refkey) {
    MVert *mvert = me->mvert;

    for (a = 0; a < me->totvert; a++, mvert++) {
      copy_v3_v3(mvert->co, vertCos[a]);
    }

    BKE_mesh_calc_normals(me);
  }

  /* apply new coords on active key block, no need to re-allocate kb->data here! */
  BKE_keyblock_update_from_vertcos(ob, kb, vertCos);
}

/* Note: we do the topology update before any brush actions to avoid
 * issues with the proxies. The size of the proxy can't change, so
 * topology must be updated first. */
static void sculpt_topology_update(Sculpt *sd,
                                   Object *ob,
                                   Brush *brush,
                                   UnifiedPaintSettings *UNUSED(ups))
{
  SculptSession *ss = ob->sculpt;

  int n, totnode;
  /* Build a list of all nodes that are potentially within the brush's area of influence */
  const bool use_original = sculpt_tool_needs_original(brush->sculpt_tool) ? true :
                                                                             ss->cache->original;
  const float radius_scale = 1.25f;
  PBVHNode **nodes = sculpt_pbvh_gather_generic(
      ob, sd, brush, use_original, radius_scale, &totnode);

  /* Only act if some verts are inside the brush area */
  if (totnode) {
    PBVHTopologyUpdateMode mode = 0;
    float location[3];

    if (!(sd->flags & SCULPT_DYNTOPO_DETAIL_MANUAL)) {
      if (sd->flags & SCULPT_DYNTOPO_SUBDIVIDE) {
        mode |= PBVH_Subdivide;
      }

      if ((sd->flags & SCULPT_DYNTOPO_COLLAPSE) || (brush->sculpt_tool == SCULPT_TOOL_SIMPLIFY)) {
        mode |= PBVH_Collapse;
      }
    }

    for (n = 0; n < totnode; n++) {
      sculpt_undo_push_node(ob,
                            nodes[n],
                            brush->sculpt_tool == SCULPT_TOOL_MASK ? SCULPT_UNDO_MASK :
                                                                     SCULPT_UNDO_COORDS);
      BKE_pbvh_node_mark_update(nodes[n]);

      if (BKE_pbvh_type(ss->pbvh) == PBVH_BMESH) {
        BKE_pbvh_node_mark_topology_update(nodes[n]);
        BKE_pbvh_bmesh_node_save_orig(nodes[n]);
      }
    }

    if (BKE_pbvh_type(ss->pbvh) == PBVH_BMESH) {
      BKE_pbvh_bmesh_update_topology(ss->pbvh,
                                     mode,
                                     ss->cache->location,
                                     ss->cache->view_normal,
                                     ss->cache->radius,
                                     (brush->flag & BRUSH_FRONTFACE) != 0,
                                     (brush->falloff_shape != PAINT_FALLOFF_SHAPE_SPHERE));
    }

    MEM_freeN(nodes);

    /* update average stroke position */
    copy_v3_v3(location, ss->cache->true_location);
    mul_m4_v3(ob->obmat, location);
  }
}

static void do_brush_action_task_cb(void *__restrict userdata,
                                    const int n,
                                    const ParallelRangeTLS *__restrict UNUSED(tls))
{
  SculptThreadedTaskData *data = userdata;

  sculpt_undo_push_node(data->ob,
                        data->nodes[n],
                        data->brush->sculpt_tool == SCULPT_TOOL_MASK ? SCULPT_UNDO_MASK :
                                                                       SCULPT_UNDO_COORDS);
  BKE_pbvh_node_mark_update(data->nodes[n]);
}

static void do_brush_action(Sculpt *sd, Object *ob, Brush *brush, UnifiedPaintSettings *ups)
{
  SculptSession *ss = ob->sculpt;
  int totnode;

  /* Build a list of all nodes that are potentially within the brush's area of influence */
  const bool use_original = sculpt_tool_needs_original(brush->sculpt_tool) ? true :
                                                                             ss->cache->original;
  const float radius_scale = 1.0f;
  PBVHNode **nodes = sculpt_pbvh_gather_generic(
      ob, sd, brush, use_original, radius_scale, &totnode);

  /* Only act if some verts are inside the brush area */
  if (totnode) {
    float location[3];

    SculptThreadedTaskData task_data = {
        .sd = sd,
        .ob = ob,
        .brush = brush,
        .nodes = nodes,
    };

    ParallelRangeSettings settings;
    BLI_parallel_range_settings_defaults(&settings);
    settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
    BLI_task_parallel_range(0, totnode, &task_data, do_brush_action_task_cb, &settings);

    if (sculpt_brush_needs_normal(ss, brush)) {
      update_sculpt_normal(sd, ob, nodes, totnode);
    }

    if (brush->mtex.brush_map_mode == MTEX_MAP_MODE_AREA) {
      update_brush_local_mat(sd, ob);
    }

    /* Apply one type of brush action */
    switch (brush->sculpt_tool) {
      case SCULPT_TOOL_DRAW:
        do_draw_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_SMOOTH:
        do_smooth_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_CREASE:
        do_crease_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_BLOB:
        do_crease_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_PINCH:
        do_pinch_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_INFLATE:
        do_inflate_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_GRAB:
        do_grab_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_ROTATE:
        do_rotate_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_SNAKE_HOOK:
        do_snake_hook_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_NUDGE:
        do_nudge_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_THUMB:
        do_thumb_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_LAYER:
        do_layer_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_FLATTEN:
        do_flatten_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_CLAY:
        do_clay_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_CLAY_STRIPS:
        do_clay_strips_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_FILL:
        do_fill_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_SCRAPE:
        do_scrape_brush(sd, ob, nodes, totnode);
        break;
      case SCULPT_TOOL_MASK:
        do_mask_brush(sd, ob, nodes, totnode);
        break;
    }

    if (!ELEM(brush->sculpt_tool, SCULPT_TOOL_SMOOTH, SCULPT_TOOL_MASK) &&
        brush->autosmooth_factor > 0) {
      if (brush->flag & BRUSH_INVERSE_SMOOTH_PRESSURE) {
        smooth(
            sd, ob, nodes, totnode, brush->autosmooth_factor * (1 - ss->cache->pressure), false);
      }
      else {
        smooth(sd, ob, nodes, totnode, brush->autosmooth_factor, false);
      }
    }

    if (sculpt_brush_use_topology_rake(ss, brush)) {
      bmesh_topology_rake(sd, ob, nodes, totnode, brush->topology_rake_factor);
    }

    if (ss->cache->supports_gravity) {
      do_gravity(sd, ob, nodes, totnode, sd->gravity_factor);
    }

    MEM_freeN(nodes);

    /* update average stroke position */
    copy_v3_v3(location, ss->cache->true_location);
    mul_m4_v3(ob->obmat, location);

    add_v3_v3(ups->average_stroke_accum, location);
    ups->average_stroke_counter++;
    /* update last stroke position */
    ups->last_stroke_valid = true;
  }
}

/* flush displacement from deformed PBVH vertex to original mesh */
static void sculpt_flush_pbvhvert_deform(Object *ob, PBVHVertexIter *vd)
{
  SculptSession *ss = ob->sculpt;
  Mesh *me = ob->data;
  float disp[3], newco[3];
  int index = vd->vert_indices[vd->i];

  sub_v3_v3v3(disp, vd->co, ss->deform_cos[index]);
  mul_m3_v3(ss->deform_imats[index], disp);
  add_v3_v3v3(newco, disp, ss->orig_cos[index]);

  copy_v3_v3(ss->deform_cos[index], vd->co);
  copy_v3_v3(ss->orig_cos[index], newco);

  if (!ss->kb) {
    copy_v3_v3(me->mvert[index].co, newco);
  }
}

static void sculpt_combine_proxies_task_cb(void *__restrict userdata,
                                           const int n,
                                           const ParallelRangeTLS *__restrict UNUSED(tls))
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Sculpt *sd = data->sd;
  Object *ob = data->ob;

  /* these brushes start from original coordinates */
  const bool use_orco = ELEM(
      data->brush->sculpt_tool, SCULPT_TOOL_GRAB, SCULPT_TOOL_ROTATE, SCULPT_TOOL_THUMB);

  PBVHVertexIter vd;
  PBVHProxyNode *proxies;
  int proxy_count;
  float(*orco)[3] = NULL;

  if (use_orco && !ss->bm) {
    orco = sculpt_undo_push_node(data->ob, data->nodes[n], SCULPT_UNDO_COORDS)->co;
  }

  BKE_pbvh_node_get_proxies(data->nodes[n], &proxies, &proxy_count);

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    float val[3];
    int p;

    if (use_orco) {
      if (ss->bm) {
        copy_v3_v3(val, BM_log_original_vert_co(ss->bm_log, vd.bm_vert));
      }
      else {
        copy_v3_v3(val, orco[vd.i]);
      }
    }
    else {
      copy_v3_v3(val, vd.co);
    }

    for (p = 0; p < proxy_count; p++) {
      add_v3_v3(val, proxies[p].co[vd.i]);
    }

    sculpt_clip(sd, ss, vd.co, val);

    if (ss->modifiers_active) {
      sculpt_flush_pbvhvert_deform(ob, &vd);
    }
  }
  BKE_pbvh_vertex_iter_end;

  BKE_pbvh_node_free_proxies(data->nodes[n]);
}

static void sculpt_combine_proxies(Sculpt *sd, Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  PBVHNode **nodes;
  int totnode;

  BKE_pbvh_gather_proxies(ss->pbvh, &nodes, &totnode);

  /* first line is tools that don't support proxies */
  if (ss->cache->supports_gravity || (sculpt_tool_is_proxy_used(brush->sculpt_tool) == false)) {
    SculptThreadedTaskData data = {
        .sd = sd,
        .ob = ob,
        .brush = brush,
        .nodes = nodes,
    };

    ParallelRangeSettings settings;
    BLI_parallel_range_settings_defaults(&settings);
    settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
    BLI_task_parallel_range(0, totnode, &data, sculpt_combine_proxies_task_cb, &settings);
  }

  if (nodes) {
    MEM_freeN(nodes);
  }
}

/* copy the modified vertices from bvh to the active key */
static void sculpt_update_keyblock(Object *ob)
{
  SculptSession *ss = ob->sculpt;
  float(*vertCos)[3];

  /* Keyblock update happens after handling deformation caused by modifiers,
   * so ss->orig_cos would be updated with new stroke */
  if (ss->orig_cos) {
    vertCos = ss->orig_cos;
  }
  else {
    vertCos = BKE_pbvh_get_vertCos(ss->pbvh);
  }

  if (vertCos) {
    sculpt_vertcos_to_key(ob, ss->kb, vertCos);

    if (vertCos != ss->orig_cos) {
      MEM_freeN(vertCos);
    }
  }
}

static void sculpt_flush_stroke_deform_task_cb(void *__restrict userdata,
                                               const int n,
                                               const ParallelRangeTLS *__restrict UNUSED(tls))
{
  SculptThreadedTaskData *data = userdata;
  SculptSession *ss = data->ob->sculpt;
  Object *ob = data->ob;
  float(*vertCos)[3] = data->vertCos;

  PBVHVertexIter vd;

  BKE_pbvh_vertex_iter_begin(ss->pbvh, data->nodes[n], vd, PBVH_ITER_UNIQUE)
  {
    sculpt_flush_pbvhvert_deform(ob, &vd);

    if (vertCos) {
      int index = vd.vert_indices[vd.i];
      copy_v3_v3(vertCos[index], ss->orig_cos[index]);
    }
  }
  BKE_pbvh_vertex_iter_end;
}

/* flush displacement from deformed PBVH to original layer */
static void sculpt_flush_stroke_deform(Sculpt *sd, Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  if (sculpt_tool_is_proxy_used(brush->sculpt_tool)) {
    /* this brushes aren't using proxies, so sculpt_combine_proxies() wouldn't
     * propagate needed deformation to original base */

    int totnode;
    Mesh *me = (Mesh *)ob->data;
    PBVHNode **nodes;
    float(*vertCos)[3] = NULL;

    if (ss->kb) {
      vertCos = MEM_mallocN(sizeof(*vertCos) * me->totvert, "flushStrokeDeofrm keyVerts");

      /* mesh could have isolated verts which wouldn't be in BVH,
       * to deal with this we copy old coordinates over new ones
       * and then update coordinates for all vertices from BVH
       */
      memcpy(vertCos, ss->orig_cos, sizeof(*vertCos) * me->totvert);
    }

    BKE_pbvh_search_gather(ss->pbvh, NULL, NULL, &nodes, &totnode);

    SculptThreadedTaskData data = {
        .sd = sd,
        .ob = ob,
        .brush = brush,
        .nodes = nodes,
        .vertCos = vertCos,
    };

    ParallelRangeSettings settings;
    BLI_parallel_range_settings_defaults(&settings);
    settings.use_threading = ((sd->flags & SCULPT_USE_OPENMP) && totnode > SCULPT_THREADED_LIMIT);
    BLI_task_parallel_range(0, totnode, &data, sculpt_flush_stroke_deform_task_cb, &settings);

    if (vertCos) {
      sculpt_vertcos_to_key(ob, ss->kb, vertCos);
      MEM_freeN(vertCos);
    }

    MEM_freeN(nodes);

    /* Modifiers could depend on mesh normals, so we should update them/
     * Note, then if sculpting happens on locked key, normals should be re-calculated
     * after applying coords from keyblock on base mesh */
    BKE_mesh_calc_normals(me);
  }
  else if (ss->kb) {
    sculpt_update_keyblock(ob);
  }
}

/* Flip all the editdata across the axis/axes specified by symm. Used to
 * calculate multiple modifications to the mesh when symmetry is enabled. */
void sculpt_cache_calc_brushdata_symm(StrokeCache *cache,
                                      const char symm,
                                      const char axis,
                                      const float angle)
{
  flip_v3_v3(cache->location, cache->true_location, symm);
  flip_v3_v3(cache->last_location, cache->true_last_location, symm);
  flip_v3_v3(cache->grab_delta_symmetry, cache->grab_delta, symm);
  flip_v3_v3(cache->view_normal, cache->true_view_normal, symm);

  /* XXX This reduces the length of the grab delta if it approaches the line of symmetry
   * XXX However, a different approach appears to be needed */
#if 0
  if (sd->paint.symmetry_flags & PAINT_SYMMETRY_FEATHER) {
    float frac = 1.0f / max_overlap_count(sd);
    float reduce = (feather - frac) / (1 - frac);

    printf("feather: %f frac: %f reduce: %f\n", feather, frac, reduce);

    if (frac < 1) {
      mul_v3_fl(cache->grab_delta_symmetry, reduce);
    }
  }
#endif

  unit_m4(cache->symm_rot_mat);
  unit_m4(cache->symm_rot_mat_inv);
  zero_v3(cache->plane_offset);

  if (axis) { /* expects XYZ */
    rotate_m4(cache->symm_rot_mat, axis, angle);
    rotate_m4(cache->symm_rot_mat_inv, axis, -angle);
  }

  mul_m4_v3(cache->symm_rot_mat, cache->location);
  mul_m4_v3(cache->symm_rot_mat, cache->grab_delta_symmetry);

  if (cache->supports_gravity) {
    flip_v3_v3(cache->gravity_direction, cache->true_gravity_direction, symm);
    mul_m4_v3(cache->symm_rot_mat, cache->gravity_direction);
  }

  if (cache->is_rake_rotation_valid) {
    flip_qt_qt(cache->rake_rotation_symmetry, cache->rake_rotation, symm);
  }
}

typedef void (*BrushActionFunc)(Sculpt *sd, Object *ob, Brush *brush, UnifiedPaintSettings *ups);

static void do_tiled(
    Sculpt *sd, Object *ob, Brush *brush, UnifiedPaintSettings *ups, BrushActionFunc action)
{
  SculptSession *ss = ob->sculpt;
  StrokeCache *cache = ss->cache;
  const float radius = cache->radius;
  BoundBox *bb = BKE_object_boundbox_get(ob);
  const float *bbMin = bb->vec[0];
  const float *bbMax = bb->vec[6];
  const float *step = sd->paint.tile_offset;
  int dim;

  /* These are integer locations, for real location: multiply with step and add orgLoc.
   * So 0,0,0 is at orgLoc. */
  int start[3];
  int end[3];
  int cur[3];

  float orgLoc[3]; /* position of the "prototype" stroke for tiling */
  copy_v3_v3(orgLoc, cache->location);

  for (dim = 0; dim < 3; ++dim) {
    if ((sd->paint.symmetry_flags & (PAINT_TILE_X << dim)) && step[dim] > 0) {
      start[dim] = (bbMin[dim] - orgLoc[dim] - radius) / step[dim];
      end[dim] = (bbMax[dim] - orgLoc[dim] + radius) / step[dim];
    }
    else {
      start[dim] = end[dim] = 0;
    }
  }

  /* first do the "untiled" position to initialize the stroke for this location */
  cache->tile_pass = 0;
  action(sd, ob, brush, ups);

  /* now do it for all the tiles */
  copy_v3_v3_int(cur, start);
  for (cur[0] = start[0]; cur[0] <= end[0]; ++cur[0]) {
    for (cur[1] = start[1]; cur[1] <= end[1]; ++cur[1]) {
      for (cur[2] = start[2]; cur[2] <= end[2]; ++cur[2]) {
        if (!cur[0] && !cur[1] && !cur[2]) {
          continue; /* skip tile at orgLoc, this was already handled before all others */
        }

        ++cache->tile_pass;

        for (dim = 0; dim < 3; ++dim) {
          cache->location[dim] = cur[dim] * step[dim] + orgLoc[dim];
          cache->plane_offset[dim] = cur[dim] * step[dim];
        }
        action(sd, ob, brush, ups);
      }
    }
  }
}

static void do_radial_symmetry(Sculpt *sd,
                               Object *ob,
                               Brush *brush,
                               UnifiedPaintSettings *ups,
                               BrushActionFunc action,
                               const char symm,
                               const int axis,
                               const float UNUSED(feather))
{
  SculptSession *ss = ob->sculpt;
  int i;

  for (i = 1; i < sd->radial_symm[axis - 'X']; ++i) {
    const float angle = 2 * M_PI * i / sd->radial_symm[axis - 'X'];
    ss->cache->radial_symmetry_pass = i;
    sculpt_cache_calc_brushdata_symm(ss->cache, symm, axis, angle);
    do_tiled(sd, ob, brush, ups, action);
  }
}

/* noise texture gives different values for the same input coord; this
 * can tear a multires mesh during sculpting so do a stitch in this
 * case */
static void sculpt_fix_noise_tear(Sculpt *sd, Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  MTex *mtex = &brush->mtex;

  if (ss->multires && mtex->tex && mtex->tex->type == TEX_NOISE) {
    multires_stitch_grids(ob);
  }
}

static void do_symmetrical_brush_actions(Sculpt *sd,
                                         Object *ob,
                                         BrushActionFunc action,
                                         UnifiedPaintSettings *ups)
{
  Brush *brush = BKE_paint_brush(&sd->paint);
  SculptSession *ss = ob->sculpt;
  StrokeCache *cache = ss->cache;
  const char symm = sd->paint.symmetry_flags & PAINT_SYMM_AXIS_ALL;
  int i;

  float feather = calc_symmetry_feather(sd, ss->cache);

  cache->bstrength = brush_strength(sd, cache, feather, ups);
  cache->symmetry = symm;

  /* symm is a bit combination of XYZ -
   * 1 is mirror X; 2 is Y; 3 is XY; 4 is Z; 5 is XZ; 6 is YZ; 7 is XYZ */
  for (i = 0; i <= symm; ++i) {
    if (i == 0 || (symm & i && (symm != 5 || i != 3) && (symm != 6 || (i != 3 && i != 5)))) {
      cache->mirror_symmetry_pass = i;
      cache->radial_symmetry_pass = 0;

      sculpt_cache_calc_brushdata_symm(cache, i, 0, 0);
      do_tiled(sd, ob, brush, ups, action);

      do_radial_symmetry(sd, ob, brush, ups, action, i, 'X', feather);
      do_radial_symmetry(sd, ob, brush, ups, action, i, 'Y', feather);
      do_radial_symmetry(sd, ob, brush, ups, action, i, 'Z', feather);
    }
  }
}

static void sculpt_update_tex(const Scene *scene, Sculpt *sd, SculptSession *ss)
{
  Brush *brush = BKE_paint_brush(&sd->paint);
  const int radius = BKE_brush_size_get(scene, brush);

  if (ss->texcache) {
    MEM_freeN(ss->texcache);
    ss->texcache = NULL;
  }

  if (ss->tex_pool) {
    BKE_image_pool_free(ss->tex_pool);
    ss->tex_pool = NULL;
  }

  /* Need to allocate a bigger buffer for bigger brush size */
  ss->texcache_side = 2 * radius;
  if (!ss->texcache || ss->texcache_side > ss->texcache_actual) {
    ss->texcache = BKE_brush_gen_texture_cache(brush, radius, false);
    ss->texcache_actual = ss->texcache_side;
    ss->tex_pool = BKE_image_pool_new();
  }
}

bool sculpt_mode_poll(bContext *C)
{
  Object *ob = CTX_data_active_object(C);
  return ob && ob->mode & OB_MODE_SCULPT;
}

bool sculpt_mode_poll_view3d(bContext *C)
{
  return (sculpt_mode_poll(C) && CTX_wm_region_view3d(C));
}

bool sculpt_poll_view3d(bContext *C)
{
  return (sculpt_poll(C) && CTX_wm_region_view3d(C));
}

bool sculpt_poll(bContext *C)
{
  return sculpt_mode_poll(C) && paint_poll(C);
}

static const char *sculpt_tool_name(Sculpt *sd)
{
  Brush *brush = BKE_paint_brush(&sd->paint);

  switch ((eBrushSculptTool)brush->sculpt_tool) {
    case SCULPT_TOOL_DRAW:
      return "Draw Brush";
    case SCULPT_TOOL_SMOOTH:
      return "Smooth Brush";
    case SCULPT_TOOL_CREASE:
      return "Crease Brush";
    case SCULPT_TOOL_BLOB:
      return "Blob Brush";
    case SCULPT_TOOL_PINCH:
      return "Pinch Brush";
    case SCULPT_TOOL_INFLATE:
      return "Inflate Brush";
    case SCULPT_TOOL_GRAB:
      return "Grab Brush";
    case SCULPT_TOOL_NUDGE:
      return "Nudge Brush";
    case SCULPT_TOOL_THUMB:
      return "Thumb Brush";
    case SCULPT_TOOL_LAYER:
      return "Layer Brush";
    case SCULPT_TOOL_FLATTEN:
      return "Flatten Brush";
    case SCULPT_TOOL_CLAY:
      return "Clay Brush";
    case SCULPT_TOOL_CLAY_STRIPS:
      return "Clay Strips Brush";
    case SCULPT_TOOL_FILL:
      return "Fill Brush";
    case SCULPT_TOOL_SCRAPE:
      return "Scrape Brush";
    case SCULPT_TOOL_SNAKE_HOOK:
      return "Snake Hook Brush";
    case SCULPT_TOOL_ROTATE:
      return "Rotate Brush";
    case SCULPT_TOOL_MASK:
      return "Mask Brush";
    case SCULPT_TOOL_SIMPLIFY:
      return "Simplify Brush";
  }

  return "Sculpting";
}

/**
 * Operator for applying a stroke (various attributes including mouse path)
 * using the current brush. */

void sculpt_cache_free(StrokeCache *cache)
{
  if (cache->dial) {
    MEM_freeN(cache->dial);
  }
  MEM_freeN(cache);
}

/* Initialize mirror modifier clipping */
static void sculpt_init_mirror_clipping(Object *ob, SculptSession *ss)
{
  ModifierData *md;
  int i;

  for (md = ob->modifiers.first; md; md = md->next) {
    if (md->type == eModifierType_Mirror && (md->mode & eModifierMode_Realtime)) {
      MirrorModifierData *mmd = (MirrorModifierData *)md;

      if (mmd->flag & MOD_MIR_CLIPPING) {
        /* check each axis for mirroring */
        for (i = 0; i < 3; ++i) {
          if (mmd->flag & (MOD_MIR_AXIS_X << i)) {
            /* enable sculpt clipping */
            ss->cache->flag |= CLIP_X << i;

            /* update the clip tolerance */
            if (mmd->tolerance > ss->cache->clip_tolerance[i]) {
              ss->cache->clip_tolerance[i] = mmd->tolerance;
            }
          }
        }
      }
    }
  }
}

/* Initialize the stroke cache invariants from operator properties */
static void sculpt_update_cache_invariants(
    bContext *C, Sculpt *sd, SculptSession *ss, wmOperator *op, const float mouse[2])
{
  StrokeCache *cache = MEM_callocN(sizeof(StrokeCache), "stroke cache");
  Main *bmain = CTX_data_main(C);
  Scene *scene = CTX_data_scene(C);
  UnifiedPaintSettings *ups = &CTX_data_tool_settings(C)->unified_paint_settings;
  Brush *brush = BKE_paint_brush(&sd->paint);
  ViewContext *vc = paint_stroke_view_context(op->customdata);
  Object *ob = CTX_data_active_object(C);
  float mat[3][3];
  float viewDir[3] = {0.0f, 0.0f, 1.0f};
  float max_scale;
  int i;
  int mode;

  ss->cache = cache;

  /* Set scaling adjustment */
  if (brush->sculpt_tool == SCULPT_TOOL_LAYER) {
    max_scale = 1.0f;
  }
  else {
    max_scale = 0.0f;
    for (i = 0; i < 3; i++) {
      max_scale = max_ff(max_scale, fabsf(ob->scale[i]));
    }
  }
  cache->scale[0] = max_scale / ob->scale[0];
  cache->scale[1] = max_scale / ob->scale[1];
  cache->scale[2] = max_scale / ob->scale[2];

  cache->plane_trim_squared = brush->plane_trim * brush->plane_trim;

  cache->flag = 0;

  sculpt_init_mirror_clipping(ob, ss);

  /* Initial mouse location */
  if (mouse) {
    copy_v2_v2(cache->initial_mouse, mouse);
  }
  else {
    zero_v2(cache->initial_mouse);
  }

  mode = RNA_enum_get(op->ptr, "mode");
  cache->invert = mode == BRUSH_STROKE_INVERT;
  cache->alt_smooth = mode == BRUSH_STROKE_SMOOTH;
  cache->normal_weight = brush->normal_weight;

  /* interpret invert as following normal, for grab brushes */
  if (SCULPT_TOOL_HAS_NORMAL_WEIGHT(brush->sculpt_tool)) {
    if (cache->invert) {
      cache->invert = false;
      cache->normal_weight = (cache->normal_weight == 0.0f);
    }
  }

  /* not very nice, but with current events system implementation
   * we can't handle brush appearance inversion hotkey separately (sergey) */
  if (cache->invert) {
    ups->draw_inverted = true;
  }
  else {
    ups->draw_inverted = false;
  }

  /* Alt-Smooth */
  if (cache->alt_smooth) {
    if (brush->sculpt_tool == SCULPT_TOOL_MASK) {
      cache->saved_mask_brush_tool = brush->mask_tool;
      brush->mask_tool = BRUSH_MASK_SMOOTH;
    }
    else {
      Paint *p = &sd->paint;
      Brush *br;
      int size = BKE_brush_size_get(scene, brush);

      BLI_strncpy(cache->saved_active_brush_name,
                  brush->id.name + 2,
                  sizeof(cache->saved_active_brush_name));

      br = (Brush *)BKE_libblock_find_name(bmain, ID_BR, "Smooth");
      if (br) {
        BKE_paint_brush_set(p, br);
        brush = br;
        cache->saved_smooth_size = BKE_brush_size_get(scene, brush);
        BKE_brush_size_set(scene, brush, size);
        curvemapping_initialize(brush->curve);
      }
    }
  }

  copy_v2_v2(cache->mouse, cache->initial_mouse);
  copy_v2_v2(ups->tex_mouse, cache->initial_mouse);

  /* Truly temporary data that isn't stored in properties */

  cache->vc = vc;

  cache->brush = brush;

  /* cache projection matrix */
  ED_view3d_ob_project_mat_get(cache->vc->rv3d, ob, cache->projection_mat);

  invert_m4_m4(ob->imat, ob->obmat);
  copy_m3_m4(mat, cache->vc->rv3d->viewinv);
  mul_m3_v3(mat, viewDir);
  copy_m3_m4(mat, ob->imat);
  mul_m3_v3(mat, viewDir);
  normalize_v3_v3(cache->true_view_normal, viewDir);

  cache->supports_gravity =
      (!ELEM(brush->sculpt_tool, SCULPT_TOOL_MASK, SCULPT_TOOL_SMOOTH, SCULPT_TOOL_SIMPLIFY) &&
       (sd->gravity_factor > 0.0f));
  /* get gravity vector in world space */
  if (cache->supports_gravity) {
    if (sd->gravity_object) {
      Object *gravity_object = sd->gravity_object;

      copy_v3_v3(cache->true_gravity_direction, gravity_object->obmat[2]);
    }
    else {
      cache->true_gravity_direction[0] = cache->true_gravity_direction[1] = 0.0;
      cache->true_gravity_direction[2] = 1.0;
    }

    /* transform to sculpted object space */
    mul_m3_v3(mat, cache->true_gravity_direction);
    normalize_v3(cache->true_gravity_direction);
  }

  /* Initialize layer brush displacements and persistent coords */
  if (brush->sculpt_tool == SCULPT_TOOL_LAYER) {
    /* not supported yet for multires or dynamic topology */
    if (!ss->multires && !ss->bm && !ss->layer_co && (brush->flag & BRUSH_PERSISTENT)) {
      if (!ss->layer_co) {
        ss->layer_co = MEM_mallocN(sizeof(float) * 3 * ss->totvert, "sculpt mesh vertices copy");
      }

      if (ss->deform_cos) {
        memcpy(ss->layer_co, ss->deform_cos, ss->totvert);
      }
      else {
        for (i = 0; i < ss->totvert; ++i) {
          copy_v3_v3(ss->layer_co[i], ss->mvert[i].co);
        }
      }
    }

    if (ss->bm) {
      /* Free any remaining layer displacements from nodes. If not and topology changes
       * from using another tool, then next layer toolstroke
       * can access past disp array bounds */
      BKE_pbvh_free_layer_disp(ss->pbvh);
    }
  }

  /* Make copies of the mesh vertex locations and normals for some tools */
  if (brush->flag & BRUSH_ANCHORED) {
    cache->original = 1;
  }

  if (SCULPT_TOOL_HAS_ACCUMULATE(brush->sculpt_tool)) {
    if (!(brush->flag & BRUSH_ACCUMULATE)) {
      cache->original = 1;
    }
  }

  cache->first_time = 1;

#define PIXEL_INPUT_THRESHHOLD 5
  if (brush->sculpt_tool == SCULPT_TOOL_ROTATE) {
    cache->dial = BLI_dial_initialize(cache->initial_mouse, PIXEL_INPUT_THRESHHOLD);
  }

#undef PIXEL_INPUT_THRESHHOLD
}

static void sculpt_update_brush_delta(UnifiedPaintSettings *ups, Object *ob, Brush *brush)
{
  SculptSession *ss = ob->sculpt;
  StrokeCache *cache = ss->cache;
  const float mouse[2] = {
      cache->mouse[0],
      cache->mouse[1],
  };
  int tool = brush->sculpt_tool;

  if (ELEM(tool,
           SCULPT_TOOL_GRAB,
           SCULPT_TOOL_NUDGE,
           SCULPT_TOOL_CLAY_STRIPS,
           SCULPT_TOOL_SNAKE_HOOK,
           SCULPT_TOOL_THUMB) ||
      sculpt_brush_use_topology_rake(ss, brush)) {
    float grab_location[3], imat[4][4], delta[3], loc[3];

    if (cache->first_time) {
      copy_v3_v3(cache->orig_grab_location, cache->true_location);
    }
    else if (tool == SCULPT_TOOL_SNAKE_HOOK) {
      add_v3_v3(cache->true_location, cache->grab_delta);
    }

    /* compute 3d coordinate at same z from original location + mouse */
    mul_v3_m4v3(loc, ob->obmat, cache->orig_grab_location);
    ED_view3d_win_to_3d(cache->vc->v3d, cache->vc->ar, loc, mouse, grab_location);

    /* compute delta to move verts by */
    if (!cache->first_time) {
      switch (tool) {
        case SCULPT_TOOL_GRAB:
        case SCULPT_TOOL_THUMB:
          sub_v3_v3v3(delta, grab_location, cache->old_grab_location);
          invert_m4_m4(imat, ob->obmat);
          mul_mat3_m4_v3(imat, delta);
          add_v3_v3(cache->grab_delta, delta);
          break;
        case SCULPT_TOOL_CLAY_STRIPS:
        case SCULPT_TOOL_NUDGE:
        case SCULPT_TOOL_SNAKE_HOOK:
          if (brush->flag & BRUSH_ANCHORED) {
            float orig[3];
            mul_v3_m4v3(orig, ob->obmat, cache->orig_grab_location);
            sub_v3_v3v3(cache->grab_delta, grab_location, orig);
          }
          else {
            sub_v3_v3v3(cache->grab_delta, grab_location, cache->old_grab_location);
          }
          invert_m4_m4(imat, ob->obmat);
          mul_mat3_m4_v3(imat, cache->grab_delta);
          break;
        default:
          /* Use for 'Brush.topology_rake_factor'. */
          sub_v3_v3v3(cache->grab_delta, grab_location, cache->old_grab_location);
          break;
      }
    }
    else {
      zero_v3(cache->grab_delta);
    }

    if (brush->falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
      project_plane_v3_v3v3(cache->grab_delta, cache->grab_delta, ss->cache->true_view_normal);
    }

    copy_v3_v3(cache->old_grab_location, grab_location);

    if (tool == SCULPT_TOOL_GRAB) {
      copy_v3_v3(cache->anchored_location, cache->true_location);
    }
    else if (tool == SCULPT_TOOL_THUMB) {
      copy_v3_v3(cache->anchored_location, cache->orig_grab_location);
    }

    if (ELEM(tool, SCULPT_TOOL_GRAB, SCULPT_TOOL_THUMB)) {
      /* location stays the same for finding vertices in brush radius */
      copy_v3_v3(cache->true_location, cache->orig_grab_location);

      ups->draw_anchored = true;
      copy_v2_v2(ups->anchored_initial_mouse, cache->initial_mouse);
      ups->anchored_size = ups->pixel_radius;
    }

    /* handle 'rake' */
    cache->is_rake_rotation_valid = false;

    if (cache->first_time) {
      copy_v3_v3(cache->rake_data.follow_co, grab_location);
    }

    if (sculpt_brush_needs_rake_rotation(brush)) {
      cache->rake_data.follow_dist = cache->radius * SCULPT_RAKE_BRUSH_FACTOR;

      if (!is_zero_v3(cache->grab_delta)) {
        const float eps = 0.00001f;

        float v1[3], v2[3];

        copy_v3_v3(v1, cache->rake_data.follow_co);
        copy_v3_v3(v2, cache->rake_data.follow_co);
        sub_v3_v3(v2, cache->grab_delta);

        sub_v3_v3(v1, grab_location);
        sub_v3_v3(v2, grab_location);

        if ((normalize_v3(v2) > eps) && (normalize_v3(v1) > eps) &&
            (len_squared_v3v3(v1, v2) > eps)) {
          const float rake_dist_sq = len_squared_v3v3(cache->rake_data.follow_co, grab_location);
          const float rake_fade = (rake_dist_sq > SQUARE(cache->rake_data.follow_dist)) ?
                                      1.0f :
                                      sqrtf(rake_dist_sq) / cache->rake_data.follow_dist;

          float axis[3], angle;
          float tquat[4];

          rotation_between_vecs_to_quat(tquat, v1, v2);

          /* use axis-angle to scale rotation since the factor may be above 1 */
          quat_to_axis_angle(axis, &angle, tquat);
          normalize_v3(axis);

          angle *= brush->rake_factor * rake_fade;
          axis_angle_normalized_to_quat(cache->rake_rotation, axis, angle);
          cache->is_rake_rotation_valid = true;
        }
      }
      sculpt_rake_data_update(&cache->rake_data, grab_location);
    }
  }
}

/* Initialize the stroke cache variants from operator properties */
static void sculpt_update_cache_variants(bContext *C, Sculpt *sd, Object *ob, PointerRNA *ptr)
{
  Scene *scene = CTX_data_scene(C);
  UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
  SculptSession *ss = ob->sculpt;
  StrokeCache *cache = ss->cache;
  Brush *brush = BKE_paint_brush(&sd->paint);

  /* RNA_float_get_array(ptr, "location", cache->traced_location); */

  if (cache->first_time ||
      !((brush->flag & BRUSH_ANCHORED) || (brush->sculpt_tool == SCULPT_TOOL_SNAKE_HOOK) ||
        (brush->sculpt_tool == SCULPT_TOOL_ROTATE))) {
    RNA_float_get_array(ptr, "location", cache->true_location);
  }

  cache->pen_flip = RNA_boolean_get(ptr, "pen_flip");
  RNA_float_get_array(ptr, "mouse", cache->mouse);

  /* XXX: Use pressure value from first brush step for brushes which don't
   *      support strokes (grab, thumb). They depends on initial state and
   *      brush coord/pressure/etc.
   *      It's more an events design issue, which doesn't split coordinate/pressure/angle
   *      changing events. We should avoid this after events system re-design */
  if (paint_supports_dynamic_size(brush, PAINT_MODE_SCULPT) || cache->first_time) {
    cache->pressure = RNA_float_get(ptr, "pressure");
  }

  /* Truly temporary data that isn't stored in properties */
  if (cache->first_time) {
    if (!BKE_brush_use_locked_size(scene, brush)) {
      cache->initial_radius = paint_calc_object_space_radius(
          cache->vc, cache->true_location, BKE_brush_size_get(scene, brush));
      BKE_brush_unprojected_radius_set(scene, brush, cache->initial_radius);
    }
    else {
      cache->initial_radius = BKE_brush_unprojected_radius_get(scene, brush);
    }
  }

  if (BKE_brush_use_size_pressure(scene, brush) &&
      paint_supports_dynamic_size(brush, PAINT_MODE_SCULPT)) {
    cache->radius = cache->initial_radius * cache->pressure;
  }
  else {
    cache->radius = cache->initial_radius;
  }

  cache->radius_squared = cache->radius * cache->radius;

  if (brush->flag & BRUSH_ANCHORED) {
    /* true location has been calculated as part of the stroke system already here */
    if (brush->flag & BRUSH_EDGE_TO_EDGE) {
      RNA_float_get_array(ptr, "location", cache->true_location);
    }

    cache->radius = paint_calc_object_space_radius(
        cache->vc, cache->true_location, ups->pixel_radius);
    cache->radius_squared = cache->radius * cache->radius;

    copy_v3_v3(cache->anchored_location, cache->true_location);
  }

  sculpt_update_brush_delta(ups, ob, brush);

  if (brush->sculpt_tool == SCULPT_TOOL_ROTATE) {
    cache->vertex_rotation = -BLI_dial_angle(cache->dial, cache->mouse) * cache->bstrength;

    ups->draw_anchored = true;
    copy_v2_v2(ups->anchored_initial_mouse, cache->initial_mouse);
    copy_v3_v3(cache->anchored_location, cache->true_location);
    ups->anchored_size = ups->pixel_radius;
  }

  cache->special_rotation = ups->brush_rotation;
}

/* Returns true if any of the smoothing modes are active (currently
 * one of smooth brush, autosmooth, mask smooth, or shift-key
 * smooth) */
static bool sculpt_any_smooth_mode(const Brush *brush, StrokeCache *cache, int stroke_mode)
{
  return ((stroke_mode == BRUSH_STROKE_SMOOTH) || (cache && cache->alt_smooth) ||
          (brush->sculpt_tool == SCULPT_TOOL_SMOOTH) || (brush->autosmooth_factor > 0) ||
          ((brush->sculpt_tool == SCULPT_TOOL_MASK) && (brush->mask_tool == BRUSH_MASK_SMOOTH)));
}

static void sculpt_stroke_modifiers_check(const bContext *C, Object *ob, const Brush *brush)
{
  SculptSession *ss = ob->sculpt;

  if (ss->kb || ss->modifiers_active) {
    Depsgraph *depsgraph = CTX_data_depsgraph(C);
    bool need_pmap = sculpt_any_smooth_mode(brush, ss->cache, 0);
    BKE_sculpt_update_object_for_edit(depsgraph, ob, need_pmap, false);
  }
}

static void sculpt_raycast_cb(PBVHNode *node, void *data_v, float *tmin)
{
  if (BKE_pbvh_node_get_tmin(node) < *tmin) {
    SculptRaycastData *srd = data_v;
    float(*origco)[3] = NULL;
    bool use_origco = false;

    if (srd->original && srd->ss->cache) {
      if (BKE_pbvh_type(srd->ss->pbvh) == PBVH_BMESH) {
        use_origco = true;
      }
      else {
        /* intersect with coordinates from before we started stroke */
        SculptUndoNode *unode = sculpt_undo_get_node(node);
        origco = (unode) ? unode->co : NULL;
        use_origco = origco ? true : false;
      }
    }

    if (BKE_pbvh_node_raycast(srd->ss->pbvh,
                              node,
                              origco,
                              use_origco,
                              srd->ray_start,
                              &srd->isect_precalc,
                              &srd->depth)) {
      srd->hit = 1;
      *tmin = srd->depth;
    }
  }
}

static void sculpt_find_nearest_to_ray_cb(PBVHNode *node, void *data_v, float *tmin)
{
  if (BKE_pbvh_node_get_tmin(node) < *tmin) {
    SculptFindNearestToRayData *srd = data_v;
    float(*origco)[3] = NULL;
    bool use_origco = false;

    if (srd->original && srd->ss->cache) {
      if (BKE_pbvh_type(srd->ss->pbvh) == PBVH_BMESH) {
        use_origco = true;
      }
      else {
        /* intersect with coordinates from before we started stroke */
        SculptUndoNode *unode = sculpt_undo_get_node(node);
        origco = (unode) ? unode->co : NULL;
        use_origco = origco ? true : false;
      }
    }

    if (BKE_pbvh_node_find_nearest_to_ray(srd->ss->pbvh,
                                          node,
                                          origco,
                                          use_origco,
                                          srd->ray_start,
                                          srd->ray_normal,
                                          &srd->depth,
                                          &srd->dist_sq_to_ray)) {
      srd->hit = 1;
      *tmin = srd->dist_sq_to_ray;
    }
  }
}

static void sculpt_raycast_detail_cb(PBVHNode *node, void *data_v, float *tmin)
{
  if (BKE_pbvh_node_get_tmin(node) < *tmin) {
    SculptDetailRaycastData *srd = data_v;
    if (BKE_pbvh_bmesh_node_raycast_detail(
            node, srd->ray_start, &srd->isect_precalc, &srd->depth, &srd->edge_length)) {
      srd->hit = 1;
      *tmin = srd->depth;
    }
  }
}

static float sculpt_raycast_init(ViewContext *vc,
                                 const float mouse[2],
                                 float ray_start[3],
                                 float ray_end[3],
                                 float ray_normal[3],
                                 bool original)
{
  float obimat[4][4];
  float dist;
  Object *ob = vc->obact;
  RegionView3D *rv3d = vc->ar->regiondata;

  /* TODO: what if the segment is totally clipped? (return == 0) */
  ED_view3d_win_to_segment_clipped(
      vc->depsgraph, vc->ar, vc->v3d, mouse, ray_start, ray_end, true);

  invert_m4_m4(obimat, ob->obmat);
  mul_m4_v3(obimat, ray_start);
  mul_m4_v3(obimat, ray_end);

  sub_v3_v3v3(ray_normal, ray_end, ray_start);
  dist = normalize_v3(ray_normal);

  if ((rv3d->is_persp == false) &&
      /* if the ray is clipped, don't adjust its start/end */
      ((rv3d->rflag & RV3D_CLIPPING) == 0)) {
    BKE_pbvh_raycast_project_ray_root(ob->sculpt->pbvh, original, ray_start, ray_end, ray_normal);

    /* recalculate the normal */
    sub_v3_v3v3(ray_normal, ray_end, ray_start);
    dist = normalize_v3(ray_normal);
  }

  return dist;
}

/* Do a raycast in the tree to find the 3d brush location
 * (This allows us to ignore the GL depth buffer)
 * Returns 0 if the ray doesn't hit the mesh, non-zero otherwise
 */
bool sculpt_stroke_get_location(bContext *C, float out[3], const float mouse[2])
{
  Object *ob;
  SculptSession *ss;
  StrokeCache *cache;
  float ray_start[3], ray_end[3], ray_normal[3], depth;
  bool original;
  ViewContext vc;

  ED_view3d_viewcontext_init(C, &vc);

  ob = vc.obact;

  ss = ob->sculpt;
  cache = ss->cache;
  original = (cache) ? cache->original : 0;

  const Brush *brush = BKE_paint_brush(BKE_paint_get_active_from_context(C));

  sculpt_stroke_modifiers_check(C, ob, brush);

  depth = sculpt_raycast_init(&vc, mouse, ray_start, ray_end, ray_normal, original);

  bool hit = false;
  {
    SculptRaycastData srd;
    srd.ss = ob->sculpt;
    srd.ray_start = ray_start;
    srd.hit = 0;
    srd.depth = depth;
    srd.original = original;
    isect_ray_tri_watertight_v3_precalc(&srd.isect_precalc, ray_normal);

    BKE_pbvh_raycast(ss->pbvh, sculpt_raycast_cb, &srd, ray_start, ray_normal, srd.original);
    if (srd.hit) {
      hit = true;
      copy_v3_v3(out, ray_normal);
      mul_v3_fl(out, srd.depth);
      add_v3_v3(out, ray_start);
    }
  }

  if (hit == false) {
    if (ELEM(brush->falloff_shape, PAINT_FALLOFF_SHAPE_TUBE)) {
      SculptFindNearestToRayData srd = {
          .original = original,
          .ss = ob->sculpt,
          .hit = 0,
          .ray_start = ray_start,
          .ray_normal = ray_normal,
          .depth = FLT_MAX,
          .dist_sq_to_ray = FLT_MAX,
      };
      BKE_pbvh_find_nearest_to_ray(
          ss->pbvh, sculpt_find_nearest_to_ray_cb, &srd, ray_start, ray_normal, srd.original);
      if (srd.hit) {
        hit = true;
        copy_v3_v3(out, ray_normal);
        mul_v3_fl(out, srd.depth);
        add_v3_v3(out, ray_start);
      }
    }
  }

  if (cache && hit) {
    copy_v3_v3(cache->true_location, out);
  }

  return hit;
}

static void sculpt_brush_init_tex(const Scene *scene, Sculpt *sd, SculptSession *ss)
{
  Brush *brush = BKE_paint_brush(&sd->paint);
  MTex *mtex = &brush->mtex;

  /* init mtex nodes */
  if (mtex->tex && mtex->tex->nodetree) {
    /* has internal flag to detect it only does it once */
    ntreeTexBeginExecTree(mtex->tex->nodetree);
  }

  /* TODO: Shouldn't really have to do this at the start of every
   * stroke, but sculpt would need some sort of notification when
   * changes are made to the texture. */
  sculpt_update_tex(scene, sd, ss);
}

static void sculpt_brush_stroke_init(bContext *C, wmOperator *op)
{
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  Scene *scene = CTX_data_scene(C);
  Object *ob = CTX_data_active_object(C);
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  SculptSession *ss = CTX_data_active_object(C)->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);
  int mode = RNA_enum_get(op->ptr, "mode");
  bool is_smooth;
  bool need_mask = false;

  if (brush->sculpt_tool == SCULPT_TOOL_MASK) {
    need_mask = true;
  }

  view3d_operator_needs_opengl(C);
  sculpt_brush_init_tex(scene, sd, ss);

  is_smooth = sculpt_any_smooth_mode(brush, NULL, mode);
  BKE_sculpt_update_object_for_edit(depsgraph, ob, is_smooth, need_mask);
}

static void sculpt_restore_mesh(Sculpt *sd, Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Brush *brush = BKE_paint_brush(&sd->paint);

  /* Restore the mesh before continuing with anchored stroke */
  if ((brush->flag & BRUSH_ANCHORED) ||
      (brush->sculpt_tool == SCULPT_TOOL_GRAB &&
       BKE_brush_use_size_pressure(ss->cache->vc->scene, brush)) ||
      (brush->flag & BRUSH_DRAG_DOT)) {
    paint_mesh_restore_co(sd, ob);
  }
}

/* Copy the PBVH bounding box into the object's bounding box */
void sculpt_update_object_bounding_box(Object *ob)
{
  if (ob->runtime.bb) {
    float bb_min[3], bb_max[3];

    BKE_pbvh_bounding_box(ob->sculpt->pbvh, bb_min, bb_max);
    BKE_boundbox_init_from_minmax(ob->runtime.bb, bb_min, bb_max);
  }
}

static void sculpt_flush_update_step(bContext *C)
{
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;
  ARegion *ar = CTX_wm_region(C);
  MultiresModifierData *mmd = ss->multires;
  View3D *v3d = CTX_wm_view3d(C);

  if (mmd != NULL) {
    multires_mark_as_modified(depsgraph, ob, MULTIRES_COORDS_MODIFIED);
  }

  DEG_id_tag_update(&ob->id, ID_RECALC_SHADING);

  /* Only current viewport matters, slower update for all viewports will
   * be done in sculpt_flush_update_done. */
  if (!BKE_sculptsession_use_pbvh_draw(ob, v3d)) {
    /* Slow update with full dependency graph update and all that comes with it.
     * Needed when there are modifiers or full shading in the 3D viewport. */
    DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
    ED_region_tag_redraw(ar);
  }
  else {
    /* Fast path where we just update the BVH nodes that changed, and redraw
     * only the part of the 3D viewport where changes happened. */
    rcti r;

    BKE_pbvh_update_bounds(ss->pbvh, PBVH_UpdateBB);
    /* Update the object's bounding box too so that the object
     * doesn't get incorrectly clipped during drawing in
     * draw_mesh_object(). [#33790] */
    sculpt_update_object_bounding_box(ob);

    if (sculpt_get_redraw_rect(ar, CTX_wm_region_view3d(C), ob, &r)) {
      if (ss->cache) {
        ss->cache->current_r = r;
      }

      /* previous is not set in the current cache else
       * the partial rect will always grow */
      sculpt_extend_redraw_rect_previous(ob, &r);

      r.xmin += ar->winrct.xmin - 2;
      r.xmax += ar->winrct.xmin + 2;
      r.ymin += ar->winrct.ymin - 2;
      r.ymax += ar->winrct.ymin + 2;
      ED_region_tag_redraw_partial(ar, &r, true);
    }
  }
}

static void sculpt_flush_update_done(const bContext *C, Object *ob)
{
  /* After we are done drawing the stroke, check if we need to do a more
   * expensive depsgraph tag to update geometry. */
  wmWindowManager *wm = CTX_wm_manager(C);
  View3D *current_v3d = CTX_wm_view3d(C);
  SculptSession *ss = ob->sculpt;
  Mesh *mesh = ob->data;
  bool need_tag = (mesh->id.us > 1); /* Always needed for linked duplicates. */

  for (wmWindow *win = wm->windows.first; win; win = win->next) {
    bScreen *screen = WM_window_get_active_screen(win);
    for (ScrArea *sa = screen->areabase.first; sa; sa = sa->next) {
      SpaceLink *sl = sa->spacedata.first;
      if (sl->spacetype == SPACE_VIEW3D) {
        View3D *v3d = (View3D *)sl;
        if (v3d != current_v3d) {
          need_tag |= !BKE_sculptsession_use_pbvh_draw(ob, v3d);
        }
      }
    }
  }

  BKE_pbvh_update_bounds(ss->pbvh, PBVH_UpdateOriginalBB);

  if (BKE_pbvh_type(ss->pbvh) == PBVH_BMESH) {
    BKE_pbvh_bmesh_after_stroke(ss->pbvh);
  }

  /* optimization: if there is locked key and active modifiers present in */
  /* the stack, keyblock is updating at each step. otherwise we could update */
  /* keyblock only when stroke is finished */
  if (ss->kb && !ss->modifiers_active) {
    sculpt_update_keyblock(ob);
  }

  if (need_tag) {
    DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
  }
}

/* Returns whether the mouse/stylus is over the mesh (1)
 * or over the background (0) */
static bool over_mesh(bContext *C, struct wmOperator *UNUSED(op), float x, float y)
{
  float mouse[2], co[3];

  mouse[0] = x;
  mouse[1] = y;

  return sculpt_stroke_get_location(C, co, mouse);
}

static bool sculpt_stroke_test_start(bContext *C, struct wmOperator *op, const float mouse[2])
{
  /* Don't start the stroke until mouse goes over the mesh.
   * note: mouse will only be null when re-executing the saved stroke.
   * We have exception for 'exec' strokes since they may not set 'mouse',
   * only 'location', see: T52195. */
  if (((op->flag & OP_IS_INVOKE) == 0) || (mouse == NULL) ||
      over_mesh(C, op, mouse[0], mouse[1])) {
    Object *ob = CTX_data_active_object(C);
    SculptSession *ss = ob->sculpt;
    Sculpt *sd = CTX_data_tool_settings(C)->sculpt;

    ED_view3d_init_mats_rv3d(ob, CTX_wm_region_view3d(C));

    sculpt_update_cache_invariants(C, sd, ss, op, mouse);

    sculpt_undo_push_begin(sculpt_tool_name(sd));

    return 1;
  }
  else {
    return 0;
  }
}

static void sculpt_stroke_update_step(bContext *C,
                                      struct PaintStroke *UNUSED(stroke),
                                      PointerRNA *itemptr)
{
  UnifiedPaintSettings *ups = &CTX_data_tool_settings(C)->unified_paint_settings;
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;
  const Brush *brush = BKE_paint_brush(&sd->paint);

  sculpt_stroke_modifiers_check(C, ob, brush);
  sculpt_update_cache_variants(C, sd, ob, itemptr);
  sculpt_restore_mesh(sd, ob);

  if (sd->flags & (SCULPT_DYNTOPO_DETAIL_CONSTANT | SCULPT_DYNTOPO_DETAIL_MANUAL)) {
    float object_space_constant_detail = 1.0f / (sd->constant_detail * mat4_to_scale(ob->obmat));
    BKE_pbvh_bmesh_detail_size_set(ss->pbvh, object_space_constant_detail);
  }
  else if (sd->flags & SCULPT_DYNTOPO_DETAIL_BRUSH) {
    BKE_pbvh_bmesh_detail_size_set(ss->pbvh, ss->cache->radius * sd->detail_percent / 100.0f);
  }
  else {
    BKE_pbvh_bmesh_detail_size_set(ss->pbvh,
                                   (ss->cache->radius / (float)ups->pixel_radius) *
                                       (float)(sd->detail_size * U.pixelsize) / 0.4f);
  }

  if (sculpt_stroke_is_dynamic_topology(ss, brush)) {
    do_symmetrical_brush_actions(sd, ob, sculpt_topology_update, ups);
  }

  do_symmetrical_brush_actions(sd, ob, do_brush_action, ups);

  sculpt_combine_proxies(sd, ob);

  /* hack to fix noise texture tearing mesh */
  sculpt_fix_noise_tear(sd, ob);

  /* TODO(sergey): This is not really needed for the solid shading,
   * which does use pBVH drawing anyway, but texture and wireframe
   * requires this.
   *
   * Could be optimized later, but currently don't think it's so
   * much common scenario.
   *
   * Same applies to the DEG_id_tag_update() invoked from
   * sculpt_flush_update_step().
   */
  if (ss->modifiers_active) {
    sculpt_flush_stroke_deform(sd, ob);
  }
  else if (ss->kb) {
    sculpt_update_keyblock(ob);
  }

  ss->cache->first_time = false;

  /* Cleanup */
  sculpt_flush_update_step(C);
}

static void sculpt_brush_exit_tex(Sculpt *sd)
{
  Brush *brush = BKE_paint_brush(&sd->paint);
  MTex *mtex = &brush->mtex;

  if (mtex->tex && mtex->tex->nodetree) {
    ntreeTexEndExecTree(mtex->tex->nodetree->execdata);
  }
}

static void sculpt_stroke_done(const bContext *C, struct PaintStroke *UNUSED(stroke))
{
  Main *bmain = CTX_data_main(C);
  Object *ob = CTX_data_active_object(C);
  Scene *scene = CTX_data_scene(C);
  SculptSession *ss = ob->sculpt;
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;

  /* Finished */
  if (ss->cache) {
    UnifiedPaintSettings *ups = &CTX_data_tool_settings(C)->unified_paint_settings;
    Brush *brush = BKE_paint_brush(&sd->paint);
    BLI_assert(brush == ss->cache->brush); /* const, so we shouldn't change. */
    ups->draw_inverted = false;

    sculpt_stroke_modifiers_check(C, ob, brush);

    /* Alt-Smooth */
    if (ss->cache->alt_smooth) {
      if (brush->sculpt_tool == SCULPT_TOOL_MASK) {
        brush->mask_tool = ss->cache->saved_mask_brush_tool;
      }
      else {
        BKE_brush_size_set(scene, brush, ss->cache->saved_smooth_size);
        brush = (Brush *)BKE_libblock_find_name(bmain, ID_BR, ss->cache->saved_active_brush_name);
        if (brush) {
          BKE_paint_brush_set(&sd->paint, brush);
        }
      }
    }

    sculpt_cache_free(ss->cache);
    ss->cache = NULL;

    sculpt_undo_push_end();

    sculpt_flush_update_done(C, ob);

    WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);
  }

  sculpt_brush_exit_tex(sd);
}

static int sculpt_brush_stroke_invoke(bContext *C, wmOperator *op, const wmEvent *event)
{
  struct PaintStroke *stroke;
  int ignore_background_click;
  int retval;

  sculpt_brush_stroke_init(C, op);

  stroke = paint_stroke_new(C,
                            op,
                            sculpt_stroke_get_location,
                            sculpt_stroke_test_start,
                            sculpt_stroke_update_step,
                            NULL,
                            sculpt_stroke_done,
                            event->type);

  op->customdata = stroke;

  /* For tablet rotation */
  ignore_background_click = RNA_boolean_get(op->ptr, "ignore_background_click");

  if (ignore_background_click && !over_mesh(C, op, event->x, event->y)) {
    paint_stroke_data_free(op);
    return OPERATOR_PASS_THROUGH;
  }

  if ((retval = op->type->modal(C, op, event)) == OPERATOR_FINISHED) {
    paint_stroke_data_free(op);
    return OPERATOR_FINISHED;
  }
  /* add modal handler */
  WM_event_add_modal_handler(C, op);

  OPERATOR_RETVAL_CHECK(retval);
  BLI_assert(retval == OPERATOR_RUNNING_MODAL);

  return OPERATOR_RUNNING_MODAL;
}

static int sculpt_brush_stroke_exec(bContext *C, wmOperator *op)
{
  sculpt_brush_stroke_init(C, op);

  op->customdata = paint_stroke_new(C,
                                    op,
                                    sculpt_stroke_get_location,
                                    sculpt_stroke_test_start,
                                    sculpt_stroke_update_step,
                                    NULL,
                                    sculpt_stroke_done,
                                    0);

  /* frees op->customdata */
  paint_stroke_exec(C, op);

  return OPERATOR_FINISHED;
}

static void sculpt_brush_stroke_cancel(bContext *C, wmOperator *op)
{
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  const Brush *brush = BKE_paint_brush(&sd->paint);

  /* XXX Canceling strokes that way does not work with dynamic topology,
   *     user will have to do real undo for now. See T46456. */
  if (ss->cache && !sculpt_stroke_is_dynamic_topology(ss, brush)) {
    paint_mesh_restore_co(sd, ob);
  }

  paint_stroke_cancel(C, op);

  if (ss->cache) {
    sculpt_cache_free(ss->cache);
    ss->cache = NULL;
  }

  sculpt_brush_exit_tex(sd);
}

static void SCULPT_OT_brush_stroke(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Sculpt";
  ot->idname = "SCULPT_OT_brush_stroke";
  ot->description = "Sculpt a stroke into the geometry";

  /* api callbacks */
  ot->invoke = sculpt_brush_stroke_invoke;
  ot->modal = paint_stroke_modal;
  ot->exec = sculpt_brush_stroke_exec;
  ot->poll = sculpt_poll;
  ot->cancel = sculpt_brush_stroke_cancel;

  /* flags (sculpt does own undo? (ton) */
  ot->flag = OPTYPE_BLOCKING;

  /* properties */

  paint_stroke_operator_properties(ot);

  RNA_def_boolean(ot->srna,
                  "ignore_background_click",
                  0,
                  "Ignore Background Click",
                  "Clicks on the background do not start the stroke");
}

/* Reset the copy of the mesh that is being sculpted on (currently just for the layer brush) */

static int sculpt_set_persistent_base_exec(bContext *C, wmOperator *UNUSED(op))
{
  SculptSession *ss = CTX_data_active_object(C)->sculpt;

  if (ss) {
    if (ss->layer_co) {
      MEM_freeN(ss->layer_co);
    }
    ss->layer_co = NULL;
  }

  return OPERATOR_FINISHED;
}

static void SCULPT_OT_set_persistent_base(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Set Persistent Base";
  ot->idname = "SCULPT_OT_set_persistent_base";
  ot->description = "Reset the copy of the mesh that is being sculpted on";

  /* api callbacks */
  ot->exec = sculpt_set_persistent_base_exec;
  ot->poll = sculpt_mode_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

/************************** Dynamic Topology **************************/

static void sculpt_dynamic_topology_triangulate(BMesh *bm)
{
  if (bm->totloop != bm->totface * 3) {
    BM_mesh_triangulate(
        bm, MOD_TRIANGULATE_QUAD_BEAUTY, MOD_TRIANGULATE_NGON_EARCLIP, 4, false, NULL, NULL, NULL);
  }
}

void sculpt_pbvh_clear(Object *ob)
{
  SculptSession *ss = ob->sculpt;

  /* Clear out any existing DM and PBVH */
  if (ss->pbvh) {
    BKE_pbvh_free(ss->pbvh);
  }
  ss->pbvh = NULL;
  BKE_object_free_derived_caches(ob);

  /* Tag to rebuild PBVH in depsgraph. */
  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
}

void sculpt_dyntopo_node_layers_add(SculptSession *ss)
{
  int cd_node_layer_index;

  char layer_id[] = "_dyntopo_node_id";

  cd_node_layer_index = CustomData_get_named_layer_index(&ss->bm->vdata, CD_PROP_INT, layer_id);
  if (cd_node_layer_index == -1) {
    BM_data_layer_add_named(ss->bm, &ss->bm->vdata, CD_PROP_INT, layer_id);
    cd_node_layer_index = CustomData_get_named_layer_index(&ss->bm->vdata, CD_PROP_INT, layer_id);
  }

  ss->cd_vert_node_offset = CustomData_get_n_offset(
      &ss->bm->vdata,
      CD_PROP_INT,
      cd_node_layer_index - CustomData_get_layer_index(&ss->bm->vdata, CD_PROP_INT));

  ss->bm->vdata.layers[cd_node_layer_index].flag |= CD_FLAG_TEMPORARY;

  cd_node_layer_index = CustomData_get_named_layer_index(&ss->bm->pdata, CD_PROP_INT, layer_id);
  if (cd_node_layer_index == -1) {
    BM_data_layer_add_named(ss->bm, &ss->bm->pdata, CD_PROP_INT, layer_id);
    cd_node_layer_index = CustomData_get_named_layer_index(&ss->bm->pdata, CD_PROP_INT, layer_id);
  }

  ss->cd_face_node_offset = CustomData_get_n_offset(
      &ss->bm->pdata,
      CD_PROP_INT,
      cd_node_layer_index - CustomData_get_layer_index(&ss->bm->pdata, CD_PROP_INT));

  ss->bm->pdata.layers[cd_node_layer_index].flag |= CD_FLAG_TEMPORARY;
}

static void sculpt_dynamic_topology_enable_ex(Main *bmain,
                                              Depsgraph *depsgraph,
                                              Scene *scene,
                                              Object *ob)
{
  SculptSession *ss = ob->sculpt;
  Mesh *me = ob->data;
  const BMAllocTemplate allocsize = BMALLOC_TEMPLATE_FROM_ME(me);

  sculpt_pbvh_clear(ob);

  ss->bm_smooth_shading = (scene->toolsettings->sculpt->flags & SCULPT_DYNTOPO_SMOOTH_SHADING) !=
                          0;

  /* Dynamic topology doesn't ensure selection state is valid, so remove [#36280] */
  BKE_mesh_mselect_clear(me);

  /* Create triangles-only BMesh */
  ss->bm = BM_mesh_create(&allocsize,
                          &((struct BMeshCreateParams){
                              .use_toolflags = false,
                          }));

  BM_mesh_bm_from_me(ss->bm,
                     me,
                     (&(struct BMeshFromMeshParams){
                         .calc_face_normal = true,
                         .use_shapekey = true,
                         .active_shapekey = ob->shapenr,
                     }));
  sculpt_dynamic_topology_triangulate(ss->bm);
  BM_data_layer_add(ss->bm, &ss->bm->vdata, CD_PAINT_MASK);
  sculpt_dyntopo_node_layers_add(ss);
  /* make sure the data for existing faces are initialized */
  if (me->totpoly != ss->bm->totface) {
    BM_mesh_normals_update(ss->bm);
  }

  /* Enable dynamic topology */
  me->flag |= ME_SCULPT_DYNAMIC_TOPOLOGY;

  /* Enable logging for undo/redo */
  ss->bm_log = BM_log_create(ss->bm);

  /* Update dependency graph, so modifiers that depend on dyntopo being enabled
   * are re-evaluated and the PBVH is re-created */
  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
  BKE_scene_graph_update_tagged(depsgraph, bmain);
}

/* Free the sculpt BMesh and BMLog
 *
 * If 'unode' is given, the BMesh's data is copied out to the unode
 * before the BMesh is deleted so that it can be restored from */
static void sculpt_dynamic_topology_disable_ex(
    Main *bmain, Depsgraph *depsgraph, Scene *scene, Object *ob, SculptUndoNode *unode)
{
  SculptSession *ss = ob->sculpt;
  Mesh *me = ob->data;

  sculpt_pbvh_clear(ob);

  if (unode) {
    /* Free all existing custom data */
    CustomData_free(&me->vdata, me->totvert);
    CustomData_free(&me->edata, me->totedge);
    CustomData_free(&me->fdata, me->totface);
    CustomData_free(&me->ldata, me->totloop);
    CustomData_free(&me->pdata, me->totpoly);

    /* Copy over stored custom data */
    me->totvert = unode->bm_enter_totvert;
    me->totloop = unode->bm_enter_totloop;
    me->totpoly = unode->bm_enter_totpoly;
    me->totedge = unode->bm_enter_totedge;
    me->totface = 0;
    CustomData_copy(&unode->bm_enter_vdata,
                    &me->vdata,
                    CD_MASK_MESH.vmask,
                    CD_DUPLICATE,
                    unode->bm_enter_totvert);
    CustomData_copy(&unode->bm_enter_edata,
                    &me->edata,
                    CD_MASK_MESH.emask,
                    CD_DUPLICATE,
                    unode->bm_enter_totedge);
    CustomData_copy(&unode->bm_enter_ldata,
                    &me->ldata,
                    CD_MASK_MESH.lmask,
                    CD_DUPLICATE,
                    unode->bm_enter_totloop);
    CustomData_copy(&unode->bm_enter_pdata,
                    &me->pdata,
                    CD_MASK_MESH.pmask,
                    CD_DUPLICATE,
                    unode->bm_enter_totpoly);

    BKE_mesh_update_customdata_pointers(me, false);
  }
  else {
    BKE_sculptsession_bm_to_me(ob, true);
  }

  /* Clear data */
  me->flag &= ~ME_SCULPT_DYNAMIC_TOPOLOGY;

  /* typically valid but with global-undo they can be NULL, [#36234] */
  if (ss->bm) {
    BM_mesh_free(ss->bm);
    ss->bm = NULL;
  }
  if (ss->bm_log) {
    BM_log_free(ss->bm_log);
    ss->bm_log = NULL;
  }

  BKE_particlesystem_reset_all(ob);
  BKE_ptcache_object_reset(scene, ob, PTCACHE_RESET_OUTDATED);

  /* Update dependency graph, so modifiers that depend on dyntopo being enabled
   * are re-evaluated and the PBVH is re-created */
  DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
  BKE_scene_graph_update_tagged(depsgraph, bmain);
}

void sculpt_dynamic_topology_disable(bContext *C, SculptUndoNode *unode)
{
  Main *bmain = CTX_data_main(C);
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  Scene *scene = CTX_data_scene(C);
  Object *ob = CTX_data_active_object(C);
  sculpt_dynamic_topology_disable_ex(bmain, depsgraph, scene, ob, unode);
}

static void sculpt_dynamic_topology_disable_with_undo(Main *bmain,
                                                      Depsgraph *depsgraph,
                                                      Scene *scene,
                                                      Object *ob)
{
  SculptSession *ss = ob->sculpt;
  if (ss->bm) {
    sculpt_undo_push_begin("Dynamic topology disable");
    sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_DYNTOPO_END);
    sculpt_dynamic_topology_disable_ex(bmain, depsgraph, scene, ob, NULL);
    sculpt_undo_push_end();
  }
}

static void sculpt_dynamic_topology_enable_with_undo(Main *bmain,
                                                     Depsgraph *depsgraph,
                                                     Scene *scene,
                                                     Object *ob)
{
  SculptSession *ss = ob->sculpt;
  if (ss->bm == NULL) {
    sculpt_undo_push_begin("Dynamic topology enable");
    sculpt_dynamic_topology_enable_ex(bmain, depsgraph, scene, ob);
    sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_DYNTOPO_BEGIN);
    sculpt_undo_push_end();
  }
}

static int sculpt_dynamic_topology_toggle_exec(bContext *C, wmOperator *UNUSED(op))
{
  Main *bmain = CTX_data_main(C);
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  Scene *scene = CTX_data_scene(C);
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;

  WM_cursor_wait(1);

  if (ss->bm) {
    sculpt_dynamic_topology_disable_with_undo(bmain, depsgraph, scene, ob);
  }
  else {
    sculpt_dynamic_topology_enable_with_undo(bmain, depsgraph, scene, ob);
  }

  WM_cursor_wait(0);
  WM_main_add_notifier(NC_SCENE | ND_TOOLSETTINGS, NULL);

  return OPERATOR_FINISHED;
}

enum eDynTopoWarnFlag {
  DYNTOPO_WARN_VDATA = (1 << 0),
  DYNTOPO_WARN_EDATA = (1 << 1),
  DYNTOPO_WARN_LDATA = (1 << 2),
  DYNTOPO_WARN_MODIFIER = (1 << 3),
};

static int dyntopo_warning_popup(bContext *C, wmOperatorType *ot, enum eDynTopoWarnFlag flag)
{
  uiPopupMenu *pup = UI_popup_menu_begin(C, IFACE_("Warning!"), ICON_ERROR);
  uiLayout *layout = UI_popup_menu_layout(pup);

  if (flag & (DYNTOPO_WARN_VDATA | DYNTOPO_WARN_EDATA | DYNTOPO_WARN_LDATA)) {
    const char *msg_error = TIP_("Vertex Data Detected!");
    const char *msg = TIP_("Dyntopo will not preserve vertex colors, UVs, or other customdata");
    uiItemL(layout, msg_error, ICON_INFO);
    uiItemL(layout, msg, ICON_NONE);
    uiItemS(layout);
  }

  if (flag & DYNTOPO_WARN_MODIFIER) {
    const char *msg_error = TIP_("Generative Modifiers Detected!");
    const char *msg = TIP_(
        "Keeping the modifiers will increase polycount when returning to object mode");

    uiItemL(layout, msg_error, ICON_INFO);
    uiItemL(layout, msg, ICON_NONE);
    uiItemS(layout);
  }

  uiItemFullO_ptr(layout, ot, IFACE_("OK"), ICON_NONE, NULL, WM_OP_EXEC_DEFAULT, 0, NULL);

  UI_popup_menu_end(C, pup);

  return OPERATOR_INTERFACE;
}

static enum eDynTopoWarnFlag sculpt_dynamic_topology_check(Scene *scene, Object *ob)
{
  Mesh *me = ob->data;
  SculptSession *ss = ob->sculpt;

  enum eDynTopoWarnFlag flag = 0;

  BLI_assert(ss->bm == NULL);
  UNUSED_VARS_NDEBUG(ss);

  for (int i = 0; i < CD_NUMTYPES; i++) {
    if (!ELEM(i, CD_MVERT, CD_MEDGE, CD_MFACE, CD_MLOOP, CD_MPOLY, CD_PAINT_MASK, CD_ORIGINDEX)) {
      if (CustomData_has_layer(&me->vdata, i)) {
        flag |= DYNTOPO_WARN_VDATA;
      }
      if (CustomData_has_layer(&me->edata, i)) {
        flag |= DYNTOPO_WARN_EDATA;
      }
      if (CustomData_has_layer(&me->ldata, i)) {
        flag |= DYNTOPO_WARN_LDATA;
      }
    }
  }

  {
    VirtualModifierData virtualModifierData;
    ModifierData *md = modifiers_getVirtualModifierList(ob, &virtualModifierData);

    /* exception for shape keys because we can edit those */
    for (; md; md = md->next) {
      const ModifierTypeInfo *mti = modifierType_getInfo(md->type);
      if (!modifier_isEnabled(scene, md, eModifierMode_Realtime)) {
        continue;
      }

      if (mti->type == eModifierTypeType_Constructive) {
        flag |= DYNTOPO_WARN_MODIFIER;
        break;
      }
    }
  }

  return flag;
}

static int sculpt_dynamic_topology_toggle_invoke(bContext *C,
                                                 wmOperator *op,
                                                 const wmEvent *UNUSED(event))
{
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;

  if (!ss->bm) {
    Scene *scene = CTX_data_scene(C);
    enum eDynTopoWarnFlag flag = sculpt_dynamic_topology_check(scene, ob);

    if (flag) {
      /* The mesh has customdata that will be lost, let the user confirm this is OK */
      return dyntopo_warning_popup(C, op->type, flag);
    }
  }

  return sculpt_dynamic_topology_toggle_exec(C, op);
}

static void SCULPT_OT_dynamic_topology_toggle(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Dynamic Topology Toggle";
  ot->idname = "SCULPT_OT_dynamic_topology_toggle";
  ot->description = "Dynamic topology alters the mesh topology while sculpting";

  /* api callbacks */
  ot->invoke = sculpt_dynamic_topology_toggle_invoke;
  ot->exec = sculpt_dynamic_topology_toggle_exec;
  ot->poll = sculpt_mode_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

/************************* SCULPT_OT_optimize *************************/

static int sculpt_optimize_exec(bContext *C, wmOperator *UNUSED(op))
{
  Object *ob = CTX_data_active_object(C);

  sculpt_pbvh_clear(ob);
  WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);

  return OPERATOR_FINISHED;
}

static bool sculpt_and_dynamic_topology_poll(bContext *C)
{
  Object *ob = CTX_data_active_object(C);

  return sculpt_mode_poll(C) && ob->sculpt->bm;
}

/* The BVH gets less optimal more quickly with dynamic topology than
 * regular sculpting. There is no doubt more clever stuff we can do to
 * optimize it on the fly, but for now this gives the user a nicer way
 * to recalculate it than toggling modes. */
static void SCULPT_OT_optimize(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Optimize";
  ot->idname = "SCULPT_OT_optimize";
  ot->description = "Recalculate the sculpt BVH to improve performance";

  /* api callbacks */
  ot->exec = sculpt_optimize_exec;
  ot->poll = sculpt_and_dynamic_topology_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

/********************* Dynamic topology symmetrize ********************/

static int sculpt_symmetrize_exec(bContext *C, wmOperator *UNUSED(op))
{
  Object *ob = CTX_data_active_object(C);
  const Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  SculptSession *ss = ob->sculpt;

  /* To simplify undo for symmetrize, all BMesh elements are logged
   * as deleted, then after symmetrize operation all BMesh elements
   * are logged as added (as opposed to attempting to store just the
   * parts that symmetrize modifies) */
  sculpt_undo_push_begin("Dynamic topology symmetrize");
  sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_DYNTOPO_SYMMETRIZE);
  BM_log_before_all_removed(ss->bm, ss->bm_log);

  BM_mesh_toolflags_set(ss->bm, true);

  /* Symmetrize and re-triangulate */
  BMO_op_callf(ss->bm,
               (BMO_FLAG_DEFAULTS & ~BMO_FLAG_RESPECT_HIDE),
               "symmetrize input=%avef direction=%i  dist=%f",
               sd->symmetrize_direction,
               0.00001f);
  sculpt_dynamic_topology_triangulate(ss->bm);

  /* bisect operator flags edges (keep tags clean for edge queue) */
  BM_mesh_elem_hflag_disable_all(ss->bm, BM_EDGE, BM_ELEM_TAG, false);

  BM_mesh_toolflags_set(ss->bm, false);

  /* Finish undo */
  BM_log_all_added(ss->bm, ss->bm_log);
  sculpt_undo_push_end();

  /* Redraw */
  sculpt_pbvh_clear(ob);
  WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);

  return OPERATOR_FINISHED;
}

static void SCULPT_OT_symmetrize(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Symmetrize";
  ot->idname = "SCULPT_OT_symmetrize";
  ot->description = "Symmetrize the topology modifications";

  /* api callbacks */
  ot->exec = sculpt_symmetrize_exec;
  ot->poll = sculpt_and_dynamic_topology_poll;
}

/**** Toggle operator for turning sculpt mode on or off ****/

static void sculpt_init_session(Depsgraph *depsgraph, Scene *scene, Object *ob)
{
  /* Create persistent sculpt mode data */
  BKE_sculpt_toolsettings_data_ensure(scene);

  ob->sculpt = MEM_callocN(sizeof(SculptSession), "sculpt session");
  ob->sculpt->mode_type = OB_MODE_SCULPT;
  BKE_sculpt_update_object_for_edit(depsgraph, ob, false, false);
}

static int ed_object_sculptmode_flush_recalc_flag(Scene *scene,
                                                  Object *ob,
                                                  MultiresModifierData *mmd)
{
  int flush_recalc = 0;
  /* multires in sculpt mode could have different from object mode subdivision level */
  flush_recalc |= mmd && mmd->sculptlvl != mmd->lvl;
  /* if object has got active modifiers, it's dm could be different in sculpt mode  */
  flush_recalc |= sculpt_has_active_modifiers(scene, ob);
  return flush_recalc;
}

void ED_object_sculptmode_enter_ex(Main *bmain,
                                   Depsgraph *depsgraph,
                                   Scene *scene,
                                   Object *ob,
                                   const bool force_dyntopo,
                                   ReportList *reports)
{
  const int mode_flag = OB_MODE_SCULPT;
  Mesh *me = BKE_mesh_from_object(ob);

  /* Enter sculptmode */
  ob->mode |= mode_flag;

  MultiresModifierData *mmd = BKE_sculpt_multires_active(scene, ob);

  const int flush_recalc = ed_object_sculptmode_flush_recalc_flag(scene, ob, mmd);

  if (flush_recalc) {
    DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
  }

  /* Create sculpt mode session data */
  if (ob->sculpt) {
    BKE_sculptsession_free(ob);
  }

  /* Make sure derived final from original object does not reference possibly
   * freed memory.
   */
  BKE_object_free_derived_caches(ob);

  sculpt_init_session(depsgraph, scene, ob);

  /* Mask layer is required */
  if (mmd) {
    /* XXX, we could attempt to support adding mask data mid-sculpt mode (with multi-res)
     * but this ends up being quite tricky (and slow) */
    BKE_sculpt_mask_layers_ensure(ob, mmd);
  }

  if (!(fabsf(ob->scale[0] - ob->scale[1]) < 1e-4f &&
        fabsf(ob->scale[1] - ob->scale[2]) < 1e-4f)) {
    BKE_report(
        reports, RPT_WARNING, "Object has non-uniform scale, sculpting may be unpredictable");
  }
  else if (is_negative_m4(ob->obmat)) {
    BKE_report(reports, RPT_WARNING, "Object has negative scale, sculpting may be unpredictable");
  }

  Paint *paint = BKE_paint_get_active_from_paintmode(scene, PAINT_MODE_SCULPT);
  BKE_paint_init(bmain, scene, PAINT_MODE_SCULPT, PAINT_CURSOR_SCULPT);

  paint_cursor_start_explicit(paint, bmain->wm.first, sculpt_poll_view3d);

  /* Check dynamic-topology flag; re-enter dynamic-topology mode when changing modes,
   * As long as no data was added that is not supported. */
  if (me->flag & ME_SCULPT_DYNAMIC_TOPOLOGY) {
    const char *message_unsupported = NULL;
    if (me->totloop != me->totpoly * 3) {
      message_unsupported = TIP_("non-triangle face");
    }
    else if (mmd != NULL) {
      message_unsupported = TIP_("multi-res modifier");
    }
    else {
      enum eDynTopoWarnFlag flag = sculpt_dynamic_topology_check(scene, ob);
      if (flag == 0) {
        /* pass */
      }
      else if (flag & DYNTOPO_WARN_VDATA) {
        message_unsupported = TIP_("vertex data");
      }
      else if (flag & DYNTOPO_WARN_EDATA) {
        message_unsupported = TIP_("edge data");
      }
      else if (flag & DYNTOPO_WARN_LDATA) {
        message_unsupported = TIP_("face data");
      }
      else if (flag & DYNTOPO_WARN_MODIFIER) {
        message_unsupported = TIP_("constructive modifier");
      }
      else {
        BLI_assert(0);
      }
    }

    if ((message_unsupported == NULL) || force_dyntopo) {
      /* Needed because we may be entering this mode before the undo system loads. */
      wmWindowManager *wm = bmain->wm.first;
      bool has_undo = wm->undo_stack != NULL;
      /* undo push is needed to prevent memory leak */
      if (has_undo) {
        sculpt_undo_push_begin("Dynamic topology enable");
      }
      sculpt_dynamic_topology_enable_ex(bmain, depsgraph, scene, ob);
      if (has_undo) {
        sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_DYNTOPO_BEGIN);
        sculpt_undo_push_end();
      }
    }
    else {
      BKE_reportf(
          reports, RPT_WARNING, "Dynamic Topology found: %s, disabled", message_unsupported);
      me->flag &= ~ME_SCULPT_DYNAMIC_TOPOLOGY;
    }
  }

  /* Flush object mode. */
  DEG_id_tag_update(&ob->id, ID_RECALC_COPY_ON_WRITE);
}

void ED_object_sculptmode_enter(struct bContext *C, ReportList *reports)
{
  Main *bmain = CTX_data_main(C);
  Scene *scene = CTX_data_scene(C);
  ViewLayer *view_layer = CTX_data_view_layer(C);
  Object *ob = OBACT(view_layer);
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  ED_object_sculptmode_enter_ex(bmain, depsgraph, scene, ob, false, reports);
}

void ED_object_sculptmode_exit_ex(Main *bmain, Depsgraph *depsgraph, Scene *scene, Object *ob)
{
  const int mode_flag = OB_MODE_SCULPT;
  Mesh *me = BKE_mesh_from_object(ob);

  MultiresModifierData *mmd = BKE_sculpt_multires_active(scene, ob);
  if (mmd) {
    multires_force_update(ob);
  }

  /* Not needed for now. */
#if 0
  const int flush_recalc = ed_object_sculptmode_flush_recalc_flag(scene, ob, mmd);
#endif

  /* Always for now, so leaving sculpt mode always ensures scene is in
   * a consistent state.
   */
  if (true || /* flush_recalc || */ (ob->sculpt && ob->sculpt->bm)) {
    DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
  }

  if (me->flag & ME_SCULPT_DYNAMIC_TOPOLOGY) {
    /* Dynamic topology must be disabled before exiting sculpt
     * mode to ensure the undo stack stays in a consistent
     * state */
    sculpt_dynamic_topology_disable_with_undo(bmain, depsgraph, scene, ob);

    /* store so we know to re-enable when entering sculpt mode */
    me->flag |= ME_SCULPT_DYNAMIC_TOPOLOGY;
  }

  /* Leave sculptmode */
  ob->mode &= ~mode_flag;

  BKE_sculptsession_free(ob);

  paint_cursor_delete_textures();

  /* Never leave derived meshes behind. */
  BKE_object_free_derived_caches(ob);

  /* Flush object mode. */
  DEG_id_tag_update(&ob->id, ID_RECALC_COPY_ON_WRITE);
}

void ED_object_sculptmode_exit(bContext *C)
{
  Main *bmain = CTX_data_main(C);
  Depsgraph *depsgraph = CTX_data_depsgraph(C);
  Scene *scene = CTX_data_scene(C);
  ViewLayer *view_layer = CTX_data_view_layer(C);
  Object *ob = OBACT(view_layer);
  ED_object_sculptmode_exit_ex(bmain, depsgraph, scene, ob);
}

static int sculpt_mode_toggle_exec(bContext *C, wmOperator *op)
{
  struct wmMsgBus *mbus = CTX_wm_message_bus(C);
  Main *bmain = CTX_data_main(C);
  Depsgraph *depsgraph = CTX_data_depsgraph_on_load(C);
  Scene *scene = CTX_data_scene(C);
  ToolSettings *ts = scene->toolsettings;
  ViewLayer *view_layer = CTX_data_view_layer(C);
  Object *ob = OBACT(view_layer);
  const int mode_flag = OB_MODE_SCULPT;
  const bool is_mode_set = (ob->mode & mode_flag) != 0;

  if (!is_mode_set) {
    if (!ED_object_mode_compat_set(C, ob, mode_flag, op->reports)) {
      return OPERATOR_CANCELLED;
    }
  }

  if (is_mode_set) {
    ED_object_sculptmode_exit_ex(bmain, depsgraph, scene, ob);
  }
  else {
    ED_object_sculptmode_enter_ex(bmain, depsgraph, scene, ob, false, op->reports);
    BKE_paint_toolslots_brush_validate(bmain, &ts->sculpt->paint);
  }

  WM_event_add_notifier(C, NC_SCENE | ND_MODE, scene);

  WM_msg_publish_rna_prop(mbus, &ob->id, ob, Object, mode);

  WM_toolsystem_update_from_context_view3d(C);

  return OPERATOR_FINISHED;
}

static void SCULPT_OT_sculptmode_toggle(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Sculpt Mode";
  ot->idname = "SCULPT_OT_sculptmode_toggle";
  ot->description = "Toggle sculpt mode in 3D view";

  /* api callbacks */
  ot->exec = sculpt_mode_toggle_exec;
  ot->poll = ED_operator_object_active_editable_mesh;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO | OPTYPE_USE_EVAL_DATA;
}

static bool sculpt_and_constant_or_manual_detail_poll(bContext *C)
{
  Object *ob = CTX_data_active_object(C);
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;

  return sculpt_mode_poll(C) && ob->sculpt->bm &&
         (sd->flags & (SCULPT_DYNTOPO_DETAIL_CONSTANT | SCULPT_DYNTOPO_DETAIL_MANUAL));
}

static int sculpt_detail_flood_fill_exec(bContext *C, wmOperator *UNUSED(op))
{
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  Object *ob = CTX_data_active_object(C);
  SculptSession *ss = ob->sculpt;
  float size;
  float bb_min[3], bb_max[3], center[3], dim[3];
  int i, totnodes;
  PBVHNode **nodes;

  BKE_pbvh_search_gather(ss->pbvh, NULL, NULL, &nodes, &totnodes);

  if (!totnodes) {
    return OPERATOR_CANCELLED;
  }

  for (i = 0; i < totnodes; i++) {
    BKE_pbvh_node_mark_topology_update(nodes[i]);
  }
  /* get the bounding box, it's center and size */
  BKE_pbvh_bounding_box(ob->sculpt->pbvh, bb_min, bb_max);
  add_v3_v3v3(center, bb_min, bb_max);
  mul_v3_fl(center, 0.5f);
  sub_v3_v3v3(dim, bb_max, bb_min);
  size = max_fff(dim[0], dim[1], dim[2]);

  /* update topology size */
  float object_space_constant_detail = 1.0f / (sd->constant_detail * mat4_to_scale(ob->obmat));
  BKE_pbvh_bmesh_detail_size_set(ss->pbvh, object_space_constant_detail);

  sculpt_undo_push_begin("Dynamic topology flood fill");
  sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_COORDS);

  while (BKE_pbvh_bmesh_update_topology(
      ss->pbvh, PBVH_Collapse | PBVH_Subdivide, center, NULL, size, false, false)) {
    for (i = 0; i < totnodes; i++) {
      BKE_pbvh_node_mark_topology_update(nodes[i]);
    }
  }

  MEM_freeN(nodes);
  sculpt_undo_push_end();

  /* force rebuild of pbvh for better BB placement */
  sculpt_pbvh_clear(ob);
  /* Redraw */
  WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);

  return OPERATOR_FINISHED;
}

static void SCULPT_OT_detail_flood_fill(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Detail Flood Fill";
  ot->idname = "SCULPT_OT_detail_flood_fill";
  ot->description = "Flood fill the mesh with the selected detail setting";

  /* api callbacks */
  ot->exec = sculpt_detail_flood_fill_exec;
  ot->poll = sculpt_and_constant_or_manual_detail_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

static void sample_detail(bContext *C, int mx, int my)
{
  /* Find 3D view to pick from. */
  bScreen *screen = CTX_wm_screen(C);
  ScrArea *sa = BKE_screen_find_area_xy(screen, SPACE_VIEW3D, mx, my);
  ARegion *ar = (sa) ? BKE_area_find_region_xy(sa, RGN_TYPE_WINDOW, mx, my) : NULL;
  if (ar == NULL) {
    return;
  }

  /* Set context to 3D view. */
  ScrArea *prev_sa = CTX_wm_area(C);
  ARegion *prev_ar = CTX_wm_region(C);
  CTX_wm_area_set(C, sa);
  CTX_wm_region_set(C, ar);

  ViewContext vc;
  ED_view3d_viewcontext_init(C, &vc);

  /* Pick sample detail. */
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
  Object *ob = vc.obact;
  Brush *brush = BKE_paint_brush(&sd->paint);

  sculpt_stroke_modifiers_check(C, ob, brush);

  float mouse[2] = {mx - ar->winrct.xmin, my - ar->winrct.ymin};
  float ray_start[3], ray_end[3], ray_normal[3];
  float depth = sculpt_raycast_init(&vc, mouse, ray_start, ray_end, ray_normal, false);

  SculptDetailRaycastData srd;
  srd.hit = 0;
  srd.ray_start = ray_start;
  srd.depth = depth;
  srd.edge_length = 0.0f;
  isect_ray_tri_watertight_v3_precalc(&srd.isect_precalc, ray_normal);

  BKE_pbvh_raycast(ob->sculpt->pbvh, sculpt_raycast_detail_cb, &srd, ray_start, ray_normal, false);

  if (srd.hit && srd.edge_length > 0.0f) {
    /* Convert edge length to world space detail resolution. */
    sd->constant_detail = 1 / (srd.edge_length * mat4_to_scale(ob->obmat));
  }

  /* Restore context. */
  CTX_wm_area_set(C, prev_sa);
  CTX_wm_region_set(C, prev_ar);
}

static int sculpt_sample_detail_size_exec(bContext *C, wmOperator *op)
{
  int ss_co[2];
  RNA_int_get_array(op->ptr, "location", ss_co);
  sample_detail(C, ss_co[0], ss_co[1]);
  return OPERATOR_FINISHED;
}

static int sculpt_sample_detail_size_invoke(bContext *C, wmOperator *op, const wmEvent *UNUSED(e))
{
  ED_workspace_status_text(C, TIP_("Click on the mesh to set the detail"));
  WM_cursor_modal_set(CTX_wm_window(C), BC_EYEDROPPER_CURSOR);
  WM_event_add_modal_handler(C, op);
  return OPERATOR_RUNNING_MODAL;
}

static int sculpt_sample_detail_size_modal(bContext *C, wmOperator *op, const wmEvent *event)
{
  switch (event->type) {
    case LEFTMOUSE:
      if (event->val == KM_PRESS) {
        int ss_co[2] = {event->x, event->y};

        sample_detail(C, ss_co[0], ss_co[1]);

        RNA_int_set_array(op->ptr, "location", ss_co);
        WM_cursor_modal_restore(CTX_wm_window(C));
        ED_workspace_status_text(C, NULL);
        WM_main_add_notifier(NC_SCENE | ND_TOOLSETTINGS, NULL);

        return OPERATOR_FINISHED;
      }
      break;

    case RIGHTMOUSE: {
      WM_cursor_modal_restore(CTX_wm_window(C));
      ED_workspace_status_text(C, NULL);

      return OPERATOR_CANCELLED;
    }
  }

  return OPERATOR_RUNNING_MODAL;
}

static void SCULPT_OT_sample_detail_size(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Sample Detail Size";
  ot->idname = "SCULPT_OT_sample_detail_size";
  ot->description = "Sample the mesh detail on clicked point";

  /* api callbacks */
  ot->invoke = sculpt_sample_detail_size_invoke;
  ot->exec = sculpt_sample_detail_size_exec;
  ot->modal = sculpt_sample_detail_size_modal;
  ot->poll = sculpt_and_constant_or_manual_detail_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;

  RNA_def_int_array(ot->srna,
                    "location",
                    2,
                    NULL,
                    0,
                    SHRT_MAX,
                    "Location",
                    "Screen Coordinates of sampling",
                    0,
                    SHRT_MAX);
}

/* Dynamic-topology detail size
 *
 * This should be improved further, perhaps by showing a triangle
 * grid rather than brush alpha */
static void set_brush_rc_props(PointerRNA *ptr, const char *prop)
{
  char *path = BLI_sprintfN("tool_settings.sculpt.brush.%s", prop);
  RNA_string_set(ptr, "data_path_primary", path);
  MEM_freeN(path);
}

static int sculpt_set_detail_size_exec(bContext *C, wmOperator *UNUSED(op))
{
  Sculpt *sd = CTX_data_tool_settings(C)->sculpt;

  PointerRNA props_ptr;
  wmOperatorType *ot = WM_operatortype_find("WM_OT_radial_control", true);

  WM_operator_properties_create_ptr(&props_ptr, ot);

  if (sd->flags & (SCULPT_DYNTOPO_DETAIL_CONSTANT | SCULPT_DYNTOPO_DETAIL_MANUAL)) {
    set_brush_rc_props(&props_ptr, "constant_detail_resolution");
    RNA_string_set(
        &props_ptr, "data_path_primary", "tool_settings.sculpt.constant_detail_resolution");
  }
  else if (sd->flags & SCULPT_DYNTOPO_DETAIL_BRUSH) {
    set_brush_rc_props(&props_ptr, "constant_detail_resolution");
    RNA_string_set(&props_ptr, "data_path_primary", "tool_settings.sculpt.detail_percent");
  }
  else {
    set_brush_rc_props(&props_ptr, "detail_size");
    RNA_string_set(&props_ptr, "data_path_primary", "tool_settings.sculpt.detail_size");
  }

  WM_operator_name_call_ptr(C, ot, WM_OP_INVOKE_DEFAULT, &props_ptr);

  WM_operator_properties_free(&props_ptr);

  return OPERATOR_FINISHED;
}

static void SCULPT_OT_set_detail_size(wmOperatorType *ot)
{
  /* identifiers */
  ot->name = "Set Detail Size";
  ot->idname = "SCULPT_OT_set_detail_size";
  ot->description =
      "Set the mesh detail (either relative or constant one, depending on current dyntopo mode)";

  /* api callbacks */
  ot->exec = sculpt_set_detail_size_exec;
  ot->poll = sculpt_and_dynamic_topology_poll;

  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
}

void ED_operatortypes_sculpt(void)
{
  WM_operatortype_append(SCULPT_OT_brush_stroke);
  WM_operatortype_append(SCULPT_OT_sculptmode_toggle);
  WM_operatortype_append(SCULPT_OT_set_persistent_base);
  WM_operatortype_append(SCULPT_OT_dynamic_topology_toggle);
  WM_operatortype_append(SCULPT_OT_optimize);
  WM_operatortype_append(SCULPT_OT_symmetrize);
  WM_operatortype_append(SCULPT_OT_detail_flood_fill);
  WM_operatortype_append(SCULPT_OT_sample_detail_size);
  WM_operatortype_append(SCULPT_OT_set_detail_size);
}
